I live on a street where parking for visitors is a nightmare due to the fact that nearly everyone has a driveway (including us). Therefore when we have visitors we always let them park across our driveway. To be clear, them doing this does not affect the neighbours on either side getting in or out of their own driveways - there is no overhang whatsoever and plenty of space. One of my neighbours has asked me not to let visitors park across my driveway as (his words) it sets a bad example and makes other people think they can park across driveways (I've never seen this happen once).
AIBU to think I should be able to let visitors block my own driveway?!?!