And it costs more than just the employee's salary. The cost of an employee is often 20-30% more just because of taxes and insurance that the employer must provide (payroll and workers compensation). So even a minimum wage employee will cost close to $10 per hour.
And service areas generally require more specialized training. You don't want the fabric employee to mis-cut too much fabric or over-cut, etc. You don't want the paint employee to mis-mix the paint, etc.
Unless those departments are making enough to support those costs, then it is a good business move by Walmart. Not one that I like, but I do understand from a purely business standpoint.