The point of being an adult is to be able to handle such influences. We treat them this way in loans, in other financial matters, in other contractual matters,

The point of being an adult is to be able to handle such influences. We treat them this way in loans, in other financial matters, in other contractual matters, and even in other areas (such as those relating to sex, where 'power difference' no longer applies once someone turns 18). About the only area where we do is with drinking age (in the US) and I find that to be quite unfair. I do think our concept of adulthood is flawed and has major issues, but society will never tolerate fixing it because it would restrict rights based on abilities and many of those who are currently taken advantage of will not willingly surrender the rights that allow them to be taken advantage of.