There might be some dubious methods being used now, despite council being extremely pedantic about design at the consent stage, then multiple inspections during the build.
When I re-clad our place, I "DIY" the window flashing systems which was a very tricky time-consuming job. I worked alongside my builder and cladding contractor, I'd worked out with designer and suppliers how to get the flashing system design implemented and the order in which things had to be done. I needed to use a router to cut grooves around all frames so a barb on a flashing system could be pressed in place. Once fitted, that meant that the flashing could move >10mm but still maintain a seal. This was one of the "leaky homes" issues - they'd bung some RTV in gaps and pray - but god wasn't listening.
The subbies doing the work though - I'm working alongside them and talking to them for days on end while I'm doing that work - they're asking me why I'm bothering. They tell me that they don't cut the grooves and fit the flashing properly because it's too hard to do - instead they cut the barbs off and glue the flashings to the frame. The challenge to them wasn't to do the job properly but to pass building inspection - and in their words the building inspectors "would never notice" that the flashing was glued in place. Probably true - but doing it that way it will surely fail.