Help! New home owner here and getting my floors refinished.

This "professional" left many many scratches and I'm worried I'm getting shafted.
He keeps saying, "...this is how it always is..." or something along those lines.

Please let me know what I should do to remedy this situation. Thanks in advance!

Image #1: https://ibb.co/n76nsa
Image #2: https://ibb.co/esVrJF
Image #3: https://ibb.co/cKDdyF

EDIT: Image #4: https://ibb.co/eE3vdF

Horrible amateurish work throw him out and don't give him a penny

Is that legal? Do I have to make him fix it, or just not pay him and hire another person to fix it?

Does this person have any professional qualifications? Do they need to have a license in your state? This is not good work, but is not bad either. Another coat of poly will make the floor look better. You should have had a reference that you could have seen their work before hiring. Definitely call them to see the spots that you are not happy with, edger scratches, unsanded areas where the old finish is still present and finish with particles embedded.
Do not pay until you are happy!

It may be 'how it always is' when he does it, but that doesn't mean it is good work. If this is his standard of work then I would not let him work on it any more. Take lots of pictures. You can pay him and then chase him or take him to court to get your $ back or let him chase you if he is so inclined. You can contact the Consumer Protection Division of your State's Attorney General's Office and file a complaint. They will arbitrate on your behalf....they may also direct you to a contractor arbitration organization if there is one in your state.

These floors look terrible and need to be resanded. Looks like the person doesn't know how to sand, doesn't have right equipment (is it rented from Home Depot) and not using correct grits for pine/douglas fir.

Do you have the person's business card or contract? There should be a license # on there that you can look up. If not, in most states that's a violation anyway. Is the person licensed and insured? or, are they just incompetent?

I would bring in a local professional to fix this work so you can a) get it done right, b) move in faster and c) use to help you w/ this "contractor." Note: it's more challenging fixing a messed up job than starting from scratch.