Most likely, they aren't using a wax that will hold up to your washings.
Typically, swirlmark removers and glazes are not wash proof. A wax should be used after these products to protect their effectiveness.
A lot of auto shampoos or other soaps can strip the wax, which in turn removes the swirlmark remover/glaze. I've had very good luck with Meguiar's #62 Carwash shampoo/conditioner. $22.99 per gallon or $6.99 for 16 oz. It does not remove the wax any more than P21S shampoo, and I dare say it compares to the Zymol shampoo.