The difficulty in this statement, for me, is that radio frequency waves are not "stand alone" when considering the OP question about the Lutron Caseta wireless remotes.
The RF signal is used in a switching system . And, very obviously, the switching system is controlling the behavior of utilization equipment connected to a premises wiring (system).
read carefully -- locations for switches required by code are minimal -- all lighting systems have wiring connections to them - Lutron grafic eye, lighhtouch, radio RA -- some have optional remotes you can carry around, I do not believe if a switch location such as top & bottom of stairs is required, a portable switch fills that requirement - by allowing all switching to be portable you are forcing any future owner to adapt to that type of system --
I keep answering your questions but you have not answer for mine -- I just threw out a thought or 2 for confirmation and have not been convinced per code(yet)