Another question regarding job hire- AL

I have never had this situation to arise before and wonder if its common.
I am a new hire at AL facility. When I was presented with the employee paper-work, there is a waiver that reads something like this.
If you quit during the first 90 days, they have a right to only pay you minimum wage on your last check. They also have a right to with-hold any money spent on you pre-hire, which includes a physical, drug screen, back-ground check, CXR, training time ...ect ect. All totally about $175.00.
I went ahead and signed the form because I didn't feel I had much choice other than not take the job, although I didn't really feel good about it.
For one thing, in my interview, I was never informed of such a policy.
I understand the theory, it costs a lot to train and hire someone and have them quit a couple days later, but I've never had this happen before.
It is unusual ?