Police unfortunately don't get to decide what laws to enforce. If the government decides to ban selling loose cigarettes, then police have a duty to the people to defend the laws that our democracy produces. Police are not elected legislators.

Every law ultimately rests on the police arresting you for not complying, at some point. Otherwise, the law is meaningless.

It turns out that people don't like having their freedom taken away and often fight back against the police. It's a very dangerous job.