There are levels of quality in frames all across the spectrum, and have been forever. Two things about it, tubing and joinery. One result - more expensive frames are lighter while not giving up strength.
Even before the bike boom there were different levels of tube sets, "gas pipe" bikes at department stores and house brands of hi-tensile and straight gauge chromoly before you got to butted Reynolds or whatever. Nicer frames got forged pieces at the ends which are pretty stout without being heavy, while cheap frames get stamped ends that bend easily so they need to be pretty big.
And then there's the joinery, and that can vary a lot... Walmart bikes have terrible looking welds, but old electro-forged Schwinns were not exactly fancy but their welds look great because of the process. The people here who like old fancy Raleighs are often bemused by the brazing. But in general a nicer bike should have nicer joinery. A nice brazed bike has lugs with filed points, and upper level Cannondales have the welds smoothed out, for instance.
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Genesis 49:16-17