Okay, everyone needs to take a picture of the cashier's setup near their place. The places I know of, it's pretty unfeasible, the whole system sits behind the till-barricade and the goods go straight from beeper to bag.
You only really get access to them when they need to go into the shopping cart.
Of course, mom and pop shops work slightly differently. I think. Okay, I have no idea, they don't exist.
That's how it is most places around my area, yeah. The customer actually bagging the stuff, or an employee besides the cashier, is pretty rare. And getting more rare, actually -- five, ten years ago it was a bit more findable.
Though apparently their training or... something... is better in my neck of the woods. I've pretty much never had a problem with 'em bagging stuff unwisely. No punctured meat packaging, no squishy/breakable stuff in the wrong bag or under something, nothing like that. Occasionally there'll be leakage of one sort or another but that's almost always because I/whoever was getting it just didn't notice the stuff was set to do that from the beginning.
So far as speed goes, though, I haven't noticed much of a gain speed wise between cashier + bagger and just cashier. Scanning and putting away are basically one motion, most of the time, and sliding the whatever towards the bagger is about as much effort. And, uh. When I shop, I tend to shop for a month+ in terms of quantity, so it's not just a matter of habitually getting small amounts in one go.