Earlier quoted context omitted.
That's not capitalism, that's culture. In the USA, it's very common to return products because of a change of mind and/or complain. That isn't universal.
The fact that a retailer is willing to accept it despite not being forced to is absolutely the result of capitalism. If they don't, you buy from a competitor. This is not some hypothetical. People in the US routinely choose retailers based on their service experience. In any case, the overall retail experience is much better on west side of the Atlantic and prices are generally better too, without the need of too man…
Think about it, for example the TV sector: All companies colluded to reduce the selection of TVs to "Smart" TVs only. I can't just go and buy from a competitor, because it simply does not exist!