there's a reason reproducible builds are a thing and most compilations aren't

Depends on your compiler. You could have a compiler that deliberately uses randomised algorithms. They are often faster and easier to understand and write.

Though in practice you can get all the benefits of both determinism and (that kind of) randomisation by using a PRNG and saving the seed you are using.

It's an open question roughly on par with P vs NP whether true randomisation is ever necessary, or whether PRNGs are enough. So far we haven't found any problem or algorithm where true RNG is necessary and good PRNG ain't enough.