Because regions and industries that pay less would be mad, and they’ve got lots of congressmen.
I think a wage threshold and weighting would be best, but others think a controlled random mixing of labour markets is better for the overall economy.
A better way might be weighing based on the applying company. Give a weight based on the size of the company and another for the type of company. These weights would be assigned based on the top-most owner(s) and not the applying companies themselves.
Also add penalties for larger companies acquiring smaller companies with H1-Bs that were hired within the last X number of years. Not sure what penalties exactly. At least financial to fund the system, but probably to the weighing as well.