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.

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.