There was potential legislation and a lot of congressional probes in the mid-late 2000’s in the US that essentially forced cellular carriers to publicly admit that it cost next to nothing on their end to send SMS messages(like 10^-7^¢ per message) yet they charged insane premiums for them of 20¢ per message. This ended up being the catalyst for US carriers dropping most SMS charges to stay competitive while the rest of the world just changed over to alternate messaging services to avoid the fees instead like you said.