It's not difficult, it's just frustrating sometimes. The whole point of taking a taxi is to save time, so if I fire a shot to get out of paying and get a wanted level, now I have to steal the taxi, get out of the immediate area, get outside the circle and avoid running into cops for a minute which is sometimes impossible if there aren't many cross streets. If everything pans out correctly, it takes an extra two minutes, but if you get spotted again that's another 2 mins wasted and you're probably pretty far away from where you wanted to get in the first place.
My point is, just pay the $30 and save yourself the trouble.