If you're BigCorp™® with a Lawyer Department then that's not really a problem: you just send it off to the lawyers and continue with your day. If you're a private individual and/or small business: it very quickly becomes a trade-off.

So imagine SourceHut sues. And they win. And losing shipping company has to pay all of sourcehut's fees. There is a very real non-zero chance they will just say "lol nope, fuck you". And then what? Basically nothing you can do about it. Even in domestic cases this is true, international cases even more so.

In reality a lot of the world runs on goodwill and voluntary adherence to the rules, with not all that much little stopping bad actors from abusing things.