#1 you need grout joints.
#2 the installer pressed too hard while setting the tiles.

That does not look like a tile contractor did that. Very unacceptable. So sorry!

i don't get what I'm looking at.. why in the top pic are there spacers between the tiles, but on the one below it, the tiles have none ? how is he supposed to grout? and never mind the obvious lippage. you shouldn't have that w/these tiles.

this is just bad tile work. that all needs to come out.

Its marble installer went with 1/16", tiles are spaced look closely. Installer stayed small because they wanted to use non sanded grout.

Not a large enough trowel and I would have went 1/8 grout lines. This give you more room to deal with keeping tiles level to each other. Also pattern with those large tiles adding in all of the above equals what you have. Installer should have explained before starting job.

they could still use unsanded up to 1/8.

I have 4x16 tiles and did the 1/16 without any issue. no lippage either. hers are unsat.