Civil Service, as well as tenure, is meant to insulate government employees from political considerations. It's a benefit of the job. Like any benefit, if you want qualified young people to take up the profession, you'll either have to offer the benefit or offer monetary recompense to make up for it.
The biggest issue I see in education right now is why on Earth would anyone go into it at the primary education level? Between required lesson plans, paperwork, grading, and assigned extra curricular activities (which does happen now that teacher unions are weakened), the job is a 60-90 hour a week job. With weakened tenure, there's no real job security. You're vulnerable to lawsuits from parents. The starting pay is a joke. There is literally no community respect for the position and you're a constant bad guy for politicians looking to score points. Who on Earth wants to go into the job?
It's little wonder the burn out rate is so high for teachers.
Those are the reasons, plus a couple more-
Assigning grades with tenure separates the teacher from pressure applied by parents or coaches within the system to keep someone elligilbe. That commonly occurs.
Enforcing rules and assigning discipline is no place to be without tenure. The wrong people in a small community can have you axed in a heartbeat.
Without tenure, when a kid says, "I'll have my mom come in and she'll have your job," it no longer is an empty threat. The fact that the kid is right erases any chance of a career in this field.
You are dealing with kids that have hormone spikes and mood swings every 5 minutes. They also don't have enough experience to handle anger.
Sound like your kind of job? I'm sure there'll be plenty of openings in the coming years..