Why do some people get vanity tags to say things like the following:

'88B88B'
'66G66G'
'00OO0O'
'SS5SS5'

Those are just some examples. Sure its hard to read the tag, or even know which is a number and which is a letter. But why do people do it?

Even if you go screaming by a car @ 150mph and someone calls it in or you even go by a cop, do they even need your plate # to pull you over?

Can someone explain this to me.