I suspect it's not economic to have police on duty permanently at all stations and the y are best deployed elsehwere. After incidents such as these, I believe a standard response is to deploy police visibly to reassure people - it does not appear to have worked for Robin but I think \ assume it does for many people.

When I first went to New York, I did find it reassuring seeing police everywhere (in Manhattan anyway), I'm not bothered either way when I go now.

I would personally like to see more police presence on the ground generally (not static but patrolling \ engaging with the public) and in police cars etc but I can't see it happening.