lonerider, I think you are being a little over judgmental here. Over the years, I've had a couple of the best guys in the avalanche business leave their beacon behind. Stupid shit happens. It's like forgetting another essential piece of gear, your snowboard boots. Yet I bet just about every one here has done that once.
As far as renting beacons go, most shops these days rent a 3 antenna beacon. If you are well practiced with a digital beacon, 3 antenna beacons are about as easy as they come to use. I can grab any 3 antenna beacon off of a shelf, make sure I understand the basics of how it operates(turning it on, search mode, display functions) and be proficient searching with it in a hurry. Yes, you should do a drill down on how it works. As long as you understand beacon searches, it's a quick adjustment to use a 3 antenna beacon. Yes it's not ideal. Still better than not having one by a mile. If said place that rents beacons doesn't have 3 antenna beacons, then they are probably renting the DTS. Which has a high percentage chance of being the beacon you already own, or have used in the past.
Maybe asking the question before it has happened doesn't paint the best picture. To answer your question marcedo, yes places rent beacons, typically mountaineering, backcountry specialty shops. If you are doing more than a day in the bc, it'll add up fast. Traveling throws me off a bit too, if I am flying. I'm not using my usual gear bag where I store all my bc gear. The best advice I can say, is pack your must have items in a bag you are taking first.