It isn't a question of "ripping anyone off" and I have never written a contract with that issue in mind. If that is the objective of the contract then I don't write it -- I turn down the job and walk away.they're probably not about to rip anyone off
The question is what happens if something goes wrong. The contract is to decide how a dispute or misunderstanding is resolved. If you have a contract which is entirely one sided, then there is an ethical problem. Suppose you had a lease with a landlord which says that the tenant was bound for one full year and could not leave without paying the full year, but that the landlord could throw the tenant out at any time without notice. That contract protects the landlord, but it does not protect the tenant, so why on earth would the tenant sign it?
Similarly, if you as a minor sign a contract which obligates your client to makes payments, but which cannot be enforced against you, then you are doing something which is ethically questionable. If a question arises about the work at any time you have recourse to court, but your client does not. I don't care about your intentions, you are placing your client in an unfair position, and with all the best intentions in the world that is ethically questionable.
Somebody wants to do work for me and says he in invulernable to action should he default I don't give him my money, I tell him to take a long walk on a short pier.