You are correct. “If A then B” is a truth relationship, not necessarily a causal relationship. For example, if you have a fever, then you are ill. The fever doesn’t cause the illness, it’s a symptom (in fact in that example, B causes A). Or “If you are in Manhattan, then you are in New York City” – no causal relationship at all, just being in Manhattan necessarily means being in New York City.
If regulations are relaxed then banks will loan more money.
I do not see that as necessarily a causal relationship. The word will in the necessary condition is intriguing because it makes you think that the sufficient condition is causing the action, but do we really know that?
Sometimes it’s the other way around where the necessary condition is causing the action. For example:
If Bob is drinking water, then he is dehydrated.
If the car engine is running, then the key was turned in the ignition.
If Jim has no money, then he has spent his money already.
When I read the explanation(s) for PT30 S2 Q15 I read that the conclusion is a causal one. Therefore a necessary assumption for that argument is that something else is not causing it either.