I'm in Scotland so the regs are a bit different, albeit similar, but here all staff have to have, or be working towards, a relevant qualification. That can include apprentices but I've experienced enough inspections to know that the inspectors generally consider the experience level of the staff as a whole and would be concerned (and mark down) for having too many unqualified and inexperienced staff.
Even assuming you're paying minimum wage over a 10 hour day, that's two children's worth of your fees gone. Before you pay for premises, heat, light, food, nappies, cleaning equipment, admin staff, toys, craft stuff, trips, parents who don't pay...
Most are not making massive profits. Most are not filling out their staff with apprentices. Those which are, are shit, not the norm.