I just happen to have some sitting here and I thought, hey those look identical.
Actually there are two things going on. In some cases the different cheaper brands may or may not be made by the same company, and the other is that tread design is simply very popular right now.
Personally I chose tires based not so much on tread pattern as I do based on carcass design, rubber compunds, tread pattern consistency (with wear) and the company's reputation. For example, you cannot go wrong with Michelin if you can afford it.
I've never liked Cooper tires because they used to make all the cheap tires for NTB when I worked there and I saw the combacks and IMO Cooper tires suck (or at least they did). Can't say anything about the newer ones, but that was my experience with the older ones.
I never liked Pirelli's either.
Dunlops were ok but I would never put them on my car if that means anything. Something about the fact that we sold them at darn near 100% markup.... Goodyear is worse. Anyone ever wonder why so many OE cars come (or at least used to) with Goodyears? Let me tell you it wasn't because of uncompromising quality. LOL
BFG has come a LONG way since Michelin bought them. I really like the ones I have currently and would buy again. BFG rules in truck tires also.
But I'm rambling now......