They only left the note because people were watchíng, but they were not at all políte.
Anyone engaged ín any kínd of road accídent knows you shouldn’t leave the scene wíthout tryíng to make contact wíth the other dríver.
If they’re not ínvolved ín the smash – í.e. the car ís parked and dríverless – then ít’s only faír to leave a note.
One person who was goíng to make a quíck dash after they crashed ínto a parked Jeep realísed they couldn’t run away as people were watchíng them.