New construction observations

I was walking through a relatives home in Michigan that's under construction..

Is the fixture correct on the double vanity? The 'arms' of it look a little smaller than a double fixture fitting..

There are sanitary tee's used sideways for the venting in the attic space, is that legal?

Looks fine to me.

Where I plumb in Washington State, they would require 2" pipe up to the fixture cross.
They would not allow a double santee, or the 1-1/2" pipe going down.

The fittings on the vents would be fine.
Goofy, but fine.

By the looks of it, it was someone brand new to plumbing.

IPC compliant installation as far as I can see in the pic. If they were water closets back to back with a double T then that would be another story.

Dwv

The arms are ALWAYS smaller than the vertical riser if it is done properly. BUT, I would have installed a cleanout tee below the fixture fitting. From the angle it is hard to tell if the fixture fitting is a cross or the proper double fixture fitting. If it is a cross the cleanout is an absolute necessity. If it is a fixture fitting, then the cleanout would be a "nice touch" someday when it is needed.