>the free alternatives are also expensive, just a different type of cost
Not if you hire reasonably competent people. These days for vast majority of FOSS services all you need is an ability to spin up a VPS and run a number of simple Docker/Podman Compose commands, it can't be that hard.
Ok so they cost you reasonably competent people. Those are expensive!
Only if your company already is lacking in the domain of competence of your engineers. If that is the case, either you have bigger problems to worry about, or your product probably isn't impressive enough to begin with to warrant an addition of complex, enterprise-grade SaaS tooling.
Or they're busy working on the core product and not screwing around on something that can be bought easily.