Nearly all of them come with their own RF transmitter technology.
Why not use Bluetooth?
Bluetooth is pretty much ubiquitous on laptops … and the technology is cheap & small.
None the less, I’ve been unable to find Bluetooth mice that are sized to be comfortable with a desktop.
There are plenty of Bluetooth mice available scaled to be used with laptops.
Microsoft used to make a few Bluetooth desktop mice … but they have been phased out for some reason.
I really wish someone would make desktop oriented Bluetooth mice.