you can spend a bit more ($~150) and get a pair of jeans that are way better than a pair of Levis at ~$60, but if all you want to spend is $60 you really won't find a better quality*. Uniqlo, however, comes very close.
[1] - There are some brands that do business via preorder that will provide better quality at a similar price (Gustin comes to mind). They are covering their risk up front though (which is very different than retail and even more different than custom) and even then those companies will often end up losing money on their cheaper pairs.
That said, there may also be some room to doubt this interpretation. I'm passingly familiar with the costs that go into producing quality jeans. The very short version is that while made-to-measure at high quality is absolutely possible, it cannot reliably be done at this price point. The labor and materials costs alone at low volumes will blow out the budget.
You're right! There are two ways of looking at such things. But as it happens, I'm someone who knows. When a market player diverges very significantly from every other player, it's very possible that they're simply outperforming everyone to a shocking degree... and it's also possible that they're dealing with the same tradeoffs as everyone else.