Builder's Base: "It's just not fair!" (Well...let's talk....)
There are a lot of different sides to this story. First and foremost, as you get higher in the trophy rankings, you'll be more likely to face other players who are more advanced than you. SuperCell has told us that matches are based on trophy levels; the stronger the game, the higher it will likely be in the trophy rankings. That just makes good sense.
However...rushing is the name of the game when it comes to the Builder's Base and higher level players are represented throughout the rankings! This is a problem for many reasons, not the least of which is the fact that a lower BH level may not be able to compete.
Let's get this point out of the way right now - just because your opponent is a higher level Builder's Hall doesn't mean you cannot compete. True - a brand new BH5 vs a well heeled BH6 is pretty much always going to turn out as a loss for the BH5. That isn't typically the kind of match up you get, though.
There's a general range where each BH level resides comfortably in the trophy rankings:
BH4 1200-1800 trophies
BH5 2100-2700 trophies
BH6 3000 trophies and up
These may shift a bit periodically, but they seem to have held fairly steady these last few months.
Now, the first question to ask - why on earth would BH6 players be down in the 1000s and why should I have to fight them as a BH4 or BH5???
In some cases, these players are still in the early stages of their rush to BH6. In others...well...they're just not very good at the game. In both cases, you'll typically find that they have lower level troops and defenses. Although they have more on the game grid and you'll have to take out more structures to earn the same percentage, their weaker structures go down more quickly and are easier to take out. Their weaker troops will struggle against your structures as well.
Of course, the tangent to this question - if BH5's sweet spot is 2100-2700, how come I can't get my BH5 any higher than 2200?
Some of the same reasons - you may not yet be skilled enough to break through the ceiling, your troops and defenses may be weaker than your opponents, or maybe you just recently got to BH5 and are still working on getting things up to snuff. (The same goes for BH4, but BH5 has the more common complaint.)
All of my BH5 games have lived in the 2500-2800 trophy range within a couple weeks of upgrading to BH5. They came from near-max BH4 games, so they already had decent defenses and troops and the competition at the lower BH5 trophy rankings just wasn't very hard to beat, even with BH4 troops. The BH6 games I was fighting were all weaker BH6 games with level 3 through level 5 defenses and typically level 8 to level 10 troops.
Is this unfair? Not really - I beat these guys all day long. And I didn't just beat one or two, here and there - my games fought nearly ONLY BH6 games and I had 6 BH5 games going at one time, so we're talking 18 wins every day against these "stronger" opponents.
Think about it - that BH6 with level 1 Crushers, MultiMortar, AirBombs, and Roaster, and level 2 or 3 on everything else...is he REALLY a BH6 defensively? Is that base REALLY something your level 10 troops can't take down (or even level 8 troops)? Sure, he'll have more structures that factor into the overall destruction percentage and that gives him an advantage there, but those defenses are all of such a low level that your troops will chew through them far faster than his will get through yours, and they'll often take less damage overall. If that player is THAT rushed, how well developed do you think his troops are to even be able to take down YOUR HIGHER level structures? (Hint: Probably not very far along.)
The matches aren't unfair because the higher level players would not be where they were in the trophy rankings if they had stronger games or were better players. That means that we were actually fairly equal in skills and capabilities. There are occasional mismatches, but for the main part it works out. My underdog games always won 3 out of 5 matches or better. (Except for the exceedingly frustrating free-fall that seems to happen periodically on PvP games.)
If you find yourself drawing more difficult opponents and actually losing, though, you need to look at the losses and your game's progress. Have you taken most of your defenses to max for your BH level and are the troops in your key attack strategies also maxed for the BH level? Are you at the upper range of the trophy ranking sweet spot I mention above? If so, then it might be time to upgrade to the next BH level. The BB game does not penalize rushing like the main game used to; it's typically a stronger path forward on the BB.
If you don't have things maxed, then it might just be that you're too new, too rushed, or not quite yet skilled enough to be as successful as you feel you should be. Take a quick reality check and try your hand at some pushing for a bit; get some things upgraded and practice. Maybe you need to adjust your upgrade path - seeing a lot of air attacks but your air targeting defenses are level 1...think you know where to focus your attention. (Believe it or not, sometimes, simply logging off for a few hours is enough to get you back to wins.)
In any case, don't let it get you down or thinking the game is unfair. It's just the current meta, something that changes daily and weekly. Your game is much stronger than you think and you're almost certainly a stronger player as an underdog. Keep plugging away and you'll get there!