You're comparing apples to oranges.

Switching the ecosystem from something like Shopify to some other shop software requires a lot of manual work, and some of the stuff won't even be transferable 1:1.

Fixing some issue with your WordPress installation will require a person who can google and knows a little stuff about webservers, and maybe containers, and will usually go pretty fast, as WordPress is open source and runs almost half the internet, and almost every problem that will come up will have been solved in some StackOverflow thread or GitHub issue.

Usually though, if you run WordPress and you're not doing a lot of hacky stuff, you will not encounter problems. Vendors shutting you down, increasing their pricing, or shutting down vital features in their software, happens regularly though. And if it happens, shit hits the fan.