I've done a lot of custom tile jobs in the States. When laid correctly tile becomes part of the substrate it's laid on. If laid properly the tile will crack and shatter like hot pyrex in cold water.
Thinset doesn't have to be 1/2" thick, you don't have put the thinset on both the tile and the floor (back buttering is good for natural stone but not always necessary) but it is best practice to key in or burn the thinset on to the floor for best adhesion. If you're working with natural tiles (stone/marble/etc...) it's good to wipe the back of the tiles with a damp sponge.
The problem I find most of the time here is either:
1. The substrate isn't properly cleaned before hand. A lot of times they just sweep it and that's it. That leaves a lot of dust/dirt on the substrate.
2. They lay one tile at a time and by the time they get half way through a bucket of thinset it's already skinned over and too dry.