That one really p***es me off as well. Even if I drive carefully for the entire time they are following me, it nearly always ends up in them pulling me over and just doing a license check etc. So it's basically just driving carefully waiting for the moment that they pull you over. There is actually a legitimate reason for this, and that's doing a license/rego check over the radio - very few police vehicles actually have the in car computers. For most "metro" areas, these checks go over a dedicated inquiry channel; problem being is that there is usually a wait whilst you work you way through the que. They could pull you over immediately of course, but some people have complained that they were getting pulled over and then told to wait for up to 10 minutes for a check to come through. Complaints cause issues with the bosses, so hence the best compromise is as above. Trust me, unless there is a complete newbie copper driving, they really don't care to follow you around all day when they could be kicking it back drinking coffee somewhere.