Leaking wetroom

[wetroomhelp]

I had a wetroom fitted three years ago as part of a full refurb that has leaked on and off ever since. It was professionally installed and tanked. The contractor has come back and siliconed the interface between the tiles and the shower tray waste multiple times but this doesn't fix the problem. Whenever I've seen other wetrooms the interface doesn't look like this and doesn't rely on so much silicon to keep the joint watertight. My question is, are we missing a trim, or should the edge tiles be longer so that they finish flush with the waste? Photos are prior to the latest resiliconing attempt. re's often a trim for example

 

[Wayners]

I can see tile grout missing along the edge where tile joint meets floor.
I can't answer if correct although I'd use polymer mastic not silicone.