USERRA has many faults, but this is not an area of faults. It actually makes an unequal among equal service members.
Just in the airlines, pilot A makes far more than pilot B for same level of airline work depending on contract.
Pilot A is at ABC airlines. Pilot B is at XYZ airlines. Both are 12 year 0-4s. Both make identical pay at the military, but daily unequal pay at the airlines, but each accepted employment at their airline, with this "paid" for zero productivity at the airlines, they are now unequally paid for military same military service. Employers, large and small, need to cover this military "penalty" (Yes, airlines already complain to politicians the cost burden of military employees in DC)
The disparity does not end their either.
USERRA applies to all employees at union, non union, management, supervisory, enlisted and officer alike. Virtually every military service member employed takes service seriously enough in an all volunteer force to perform that service knowing that we do not military service to get rich. To the vast majority of Americans that have and never will serve, this highlights to these fellow employees who WILL lose benefits that the "military" employees caused this loss over time. This actually harms the all volunteer force which is actually what USERRA is designed to accomplish.
Am an ardent USERRA supporter and of fellow military service members. Many years of engagement at government, DOL, employer and union level.
This is not a long term win, in the end, it will cause employers to craft a manner to avoid hiring as many military service members as legally feasible. That is reality.