My old garage door had this weird plastic remote from like 1998. I dropped it once and the back panel popped off, just a simple green circuit board and a single battery. Felt so cheated after paying a guy seventy bucks to "program" it. All that mystery gone in one second.
Hold up, the button itself is simple but the magic is in the rolling code. Every time you press it, the remote sends a new, unique code to the opener so thieves can't just copy the signal. That's what the programming step is for, to sync that code system. So the guts look basic but there's a tiny brain making new numbers each time. Makes that seventy bucks feel slightly less bad, lol, but still a lot for a two minute sync job.