I wonder whether asking about the rationale behind a law is on-topic here.
In my opinion, no. Even Supreme Court justices disagree as to whether legislative intent can be determined, let alone be used to inform statutory interpretation.
In rare cases, an appellate court may state what they are assuming to be the purpose of a law as part of their opinion (see King v. Burwell, for example).
But generally, Politics.SE or History.SE would be better suited to answer this type of motivation/policy question.
This is my opinion and isn't representative of the other moderators or the community.
- Legislation is part of the legal process
- Explanatory memoranda (and similar documents) exist in some legislatures
- Politicians may or may not announce.publish their motivations
- More generally, each legal system will have their own principles of jurisprudence that should be used in statutory interpretation, which can be applied when answering these questions.
Also, we probably shouldn't declare questions off-topic purely because the asker isn't aware of whether something can be answered or not. It'd be like punishing someone for something they weren't sure was a crime.
What should happen, though, is that these questions will eventually become canonical questions & answers, and then subsequent ones (where warranted) will be closed as duplicates, pointing to them.
To address what nomen agentis has said, these questions would turn from : What was the motivation for the X Act? to Can I determine the motivation behind Acts passed by X? Then, subsequent questions would be closed as duplicates, and then pointed at this canonical question (for that jurisdiction).