1: The actual number of sites and the resources that go to each are decided by the State. Here's info on the number of sites TX has closed lately.
You are correct that local mistakes were made and that local officials are in charge...but they can only do so much with the resources provided by the State. Are you implying that local polling locations have taxing authority and can purchase additional machines?
2. The Republican party denied a request to have a joint primary and 1 line instead of 2 (with the other unused), which exacerbated the problem.
Local screw ups can and will happen on both sides of the aisle, but TX Republicans have set up a system designed to make it harder for people of color to vote. There is no denying that.
Link: https://www.theguardian.com/us-news/2020/mar/02/texas-polling-sites-closures-voting