Oh dear. I only do diy tiling and there is no way i'd leave it like that. Looks to me like it they were learning on the job. The problem with the door is that the tiles were not set out correctly for a start. Should avoid thin slivers like that. Don't pay- get the job corrected
Unless it's a wet room floor or trim edge you should never have cuts visible. It's obvious from the poor setting out the guy is a chancer. I score porcelain then snap over my knee with a lot of force. if the joint has to be shown I always use coarse sandpaper to create an edge almost indistinguishable from a manufactured one.
Why would anyone think its a good idea too have a cut edge on show in the middle of a tile run? Just why? Very poor workmanship, I have seen worse tho, went to quote for a kitchen a couple of years back, I say quote, didn't even bother just wanted to ask if I could use the toilet before I left as my landscaper mate mentioned how bad the guys new bathroom was. I didn't expect too find crazy paving style travetine tiles,,,,,, wish id got some pics! The guy's mate done it, apparently.