Clearly you have no idea. I have some hanes undershirts, and some polo. The polos outlast the hanes hands down, and are more comfortable the entire time. And don’t even get me started on boxer briefs. You generally get what you pay for, and although there are exceptions, your example is a TERRIBLE one.
You are trying to say that cotton is cotton. Well by that logic, rubber is rubber, and better tires would be a waste of money, because the only difference is name on the side.
The other reason BIGDOGS shirts are so cheap is because there’s no demand for that kind of gay shit.