You'll be surprised how many people will take offence or retort with 'not illegal what'. Singaporeans are used to being babied by the nanny state so they'd only take action if they have 'official' reason to back it up; we frown upon vigilantism/lack backbone. That's just our style of societal engineering - disbursements for desirable behaviour like recycling bottles and cans (even for reading books!) and fines for vices like smoking

I do it quite often but I hate that I need to do so ...

Also, I have to do a crazy assessment beforehand in case I may get stabbed or something.