Yes, public transport has always been a problem in BKK for decades. Not problem with Transport providers but more because of overall city planning and politics. The bus are quite safe. Not very comfortable when it is a non-aircon bus during the peak hours.
actually, these so called neighbourhood hooligans are just some teens looking for "high" with Yaba pills. Yes, they can be more dangerous as they are not thinking like an adults. They can get desperate and do damages even the long time gangster won't think of. Money for Yaba is only thing on their minds and so they target the weaks. Females, elderly, the weak and of course, Jackpot is Foreigners cos' it's presume that foreigners are richer.
If you are ever stop by one of these kids, just give them THB 200 and tell them this is what you have as you have spent all your money elsewhere. Be polite but firm and most likely, they will let you go.