The Telecaster was the first mass produced solid body electric and Leo Fender was really good at finding simple engineering solutions that were kind of crude but worked really well and were tough as nails.
The Tele bridge design has a stamped plate screwed to the body with holes for the strings to come through from the rear of the body. They go over brass bar saddles that are elevated from the bridge plate by grub screws and adjusted fore and aft by a longer sprung screw through the raised lip of the rear of the bridge plate.
All this was intended to be hidden under a metal cover that looked like an ashtray when it was removed (you can see where it would have been in that pic). Some models still come with the ashtray...
The three straight saddles don’t allow for particularly good intonation (you have to “split the difference” between pairs of strings) but that’s kind of the traditional Tele vibe. Nowadays you can get compensated three saddle designs or six bent steel saddles that are more like a hardtail Strat bridge.