if caulking is used, you should be able to make your stairs look quite a bit better. Although, I'd be unhappy if that's what the finished renovation looked like - I'd want the contractor to fix the issues. However, if the bid was really low, you'll probably do better job fixing the issues yourself.

Bring in a competent craftsman and pay him the cost to make this right. Just accept the cost as what it is. Necessary.

It just looks unfinished as there should be trim between stair and risers. Also there could be another layer added to the sides to finish off that area like another layer of baseboard as well as along the bottom. Get someone in to finish it. Also know that this is common the problem with replacing treads especially when removing carpeting. There is finishing that has to happen.

I just doesn't appear to be finished. There are likely some missing trim pieces. Have you contacted the person who did this to share your dissatisfaction?

Is the job finished and paid for ? If so you now need someone to fix this mess and not the guy who did this . If you have not paid in full then IMO hold back that final pay until you are happy . What you have is an unfinished job .

Op has never returned

I read the title wrong. I read it as "Staring Rhino Dilemma" and the discussion involved a problem with looking with a wide-eyed gaze at a large thick-skinned mammals having one or two upright horns on the snout.