Hmm not sure which "ghetto" you're from ?? But I'm a bit confused by your logic !!
It's OK to tag buildings as it's gives the streets "character" where as tagging private trucks/vans grinds your teeth ?? Does that mean that if someone tags your house, it would add character? If you ever own a house one day, I would love to see you add “character” to it before trying to sell it.
As for the argument of graffiti being "art" is purely subjective. But what I have problem with graffiti is that it forced upon me. Where as for example abstract or minimalist art, which is not appealing to the vast population, is NOT force upon them. If someone who like abstract or minimalist arts, they would go to an exhibition to view it. Otherwise, it’s out of sight. You do not have the same choice as graffiti.
For me, graffiti creates an impression of disorder and of lawlessness. A city that is tainted by vandalism invites more vandalism and more serious crime because it sends the message that the city doesn't care and isn't paying attention. This is an example of what happened in New York in the 70-80s, until Giuliani came into office and introduced new measures to combat crimes which eventually trickled down to graffiti.
Having said that I do think it does take talent to be a graffiti artist, but this doesn’t change my view of it being vandalism as soon as you create your work on someone’s private property without their consent, regardless on how appealing your work might be.
As for the punishment, they’re not design to be proportionate to the crime otherwise it won’t be effective. I think the more disproportionate the punitive actions are the more likely it is to succeed. Have a look at Dubai or Singapore as an example, two of the most sophisticated and modern cities in the world without graffiti problems !! They’re also not very tolerant of graffiti “artists”. BTW I’m not saying I agree with their punitive actions, but it seems to worked!!
Perhaps the saving grace here is that most graffiti “artist”, like gangster is that by the time they have family or reach their mid-20s, their priorities usually shifts and is no longer motivated to tag. This is why you don’t see too many 30yr gangsters or graffiti artists