Wow, you're right, data is technically allowed on FRS frequencies. I didn't realize that. It's not unrestricted though. There are a lot of regulations that constrain how FRS radios can work, much more than for 2.4 Ghz.
You might have conflated the prohibition on encrypted/coded communication with a blanket ban on data vs. voice. Those frequencies are supposed to be used for public communication, which has been interpreted as a requirement that anyone can listen in (as opposed to any member of the public privately communicating with any other member). See 47 CFR Part 95, plain language voice communication.
These days, I'm not sure anyone would seriously rely on a system that sent only unencrypted point-to-point data, so for that use case your original point stands.
There's also a slice of ISM spectrum available around 900-930 MHz in the US, and Europe has an equivalent one around 860 MHz, which is where the (unfortunately discontinued) Gotenna consumer device used to operate.
