The problem is that coercion does work - using wrong means.
Using force, intimidation, fear, constraint, etc to get someone to do something they don't want to seems an abuse against a person's free will.
However, convincing or persuading by offering incentives, so that one freely chooses to do something seems to respect a person's freedom of will.
This can also go too far by extending into trickery and manipulation, which while respecting a person's freedom of will, does not respect a person's intellect or trust.