If that were the case, Intel would have plenty of customers lining up for their fab services. So would Samsung. Both of them have no customers for good reasons. Their processes aren't as good as TSMC's.
Of course fab processes are different. If anyone can just buy equipment and run it with the same results, Apple would have done so on day one.
They aren't as efficient as TSMC. For the lower end chips a lower yield rate won't be as significant as the very top end chips (that already have been reported to have some weird yield efficiency issues). If TSMC fab time becomes a bottleneck with rapidly rising prices you'll see more, and more orders go to Intel and other players... oh wait that's already what's literally happening right now.