If the mob boss holds leverage over the enforcer (first a debt with threat of violence, and later evidence of the enforcer's crimes) then the enforcer might not be such a bad person. This is a big reason that lower level criminals are offered witness protection in exchange for information

I'm not sure why people keep equating carelessness with actual malice.

Yes, obviously both the boss and the enforcer are bad for doing harmful things with an evil mind. That's just not the same as apathy.

Taking actions that you know put someone else's personal property at risk _is_ malice. It's less malice than actively breaking it, but it is actively making a choice to put something that belongs to someone else in harm's way.

No, it's not. Neither is minor speeding, for example. It's a lack of care and awareness about the consequences of one's actions - hardly a desire for those consequences. You say "active" and the whole point is that it isn't.