I don't think the problem is primarily a lack of good OSS implementations or UX lacking polish. To me, it's more that there is a mismatch between what programming language/CS enthusiasts find interesting and useful, and what industry software developers find useful.

First off, the "training" problem is a very real and fundamental blocker. I think academics or less experienced engineers see it as a problem of education, but I believe it's actually an engineering/organizational problem: for a company or even OSS project, when you use niche/unadopted tools like this you either need to provide training for it or you massively shrink the set of people able to work on your project by requiring or expecting them to learn it on their own. This introduces a practical headache bigger than the ones a tool like this solves (since these are just incrementally better ways to test software) - you get less contributions or need to spend more on getting people onboarded. Note that even if "training" people is free in the sense that there is no paid training material, you still pay a cost in lower productivty for new people and the time spent training.

Even once people are trained, you now have a process/institutional need to support the property based tests you wrote. That may mean paying for licenses for software, or maintenance of whatever infrastructure/integrations you write to get property based testing working in your developer workflow. And you also now need to rely on people using these tools correctly - the problem with formal verification is that it doesn't verify that you're actually solving the real problem correctly, just that your program operates as expected (ie it only verifies that your software is Working As Implemented, not Working as Intended). The more you rely on average joes to wield complex things like this well, the more headaches you introduce - if the bottom 10% of people you hire use it sloppily or wrongly, once you're past a few dozen regular contributors you're basically going to have constant issues. You see this all the time with even just regular unit and integration tests - less capable developers constantly introduce flakes or write tests so bad/basic that it'd be better for them to not even be writing tests at all.

Even if after considering all that it still seems a worthy tradeoff, there's the question of whether property based testing solves the problem you think it does. As I mentioned, it can moreso verify software is Working as Implemented rather than Working as Intended. But there is the bigger problem of major software projects not conforming to the simpler use cases that sell people on using this tool. In my experience stateless functions almost never have bugs, and when they do, it's mostly a "requirements discovery" problem you wouldn't catch with any kind of verification tooling.

Stateful verification becomes a problem in the kinds of real systems programming projects like the Linux Kernel or Qemu which stand to benefit most from verification. If you're verifying things at the level of a "higher level" abstraction like a scheduler, you almost always have really high dimensionality/a lot of state, perhaps deceptively more than you think, because of composition. And you tend to also have a devloop that is already very slow - builds take a long time, and running tests of higher level components can be "expensive" because it may take 100ms-1s for something like a kernel to finish starting in a test environment. For a single test that's nothing, but multiplied across all tests makes testing painful enough already; adding 3x or 100x by doing property based testing with new tests, even if pruned before submitting, could be either hugely expensive or way too slow. And similarly, the increased resource requirements to maintain state machines can be very expensive. TSAN does essentially parallel property-based testing and introduces 128-512 bytes of overhead for every 8 bytes of memory under test: https://github.com/google/sanitizers/wiki/ThreadSanitizerAlg....

Is it cool and underrated? Definitely. But it's not a silver bullet and honestly just isn't worth it for most software. Even when it is worth it, it has its drawbacks.