Vaders brother

I’m near the end of an extension project and the tilers came in yesterday. They should be coming back Monday to finish eg to fix the loose ridge tiles in the pics below and do the mortaring in at the fascia. But what have they done in the first picture? They have cut the left side of the tile and butted up against the existing tiles, where I would expect them to be interlocked or under the existing tiles. The other side of the roof is fine where the tiles are laid over the existing tiles. Yes they sit a bit high but will do their job and gradually weather and darken over time. The tiles were hard to source and are not exact matches, but pretty close. We had to wait about 6 weeks for delivery due to the existing problems with the pandemic but I do feel a bit frustrated as I don’t understand why the tiles are laid like this and nothing was said on the day. Can anyone throw any light on this for me before I catch up with the tilers tomorrow? Many thanks in anticipation.