its not like they can use the off days for a second job.
That’s true, but they can use it to take care of other obligations, which might enable them to do some private tutoring during other times to bring in some extra income.
It was mentioned earlier in the discussion that rebbeim and morahs have summeres off. It should be noted that most rebbeim and some (although not as many) morahs do work during the summer months, either tutoring, or in day camps or sleep-away camps.
if parents would have more time to work maye they will be able to afford more tuition
A couple of days’ extra pay will go straight to tuition? Unlikely, to say the least.