My problem with "5 stars for everyone" was exemplified today. This morning had a great driver, got out and opened the trunk, and checked air con and radio were fine.

This evening the driver was ok, he missed a turn, added about 2 minutes to the trip, nothing major - not like the last taxi I got, but not a patch on this mornings.

How can I give this morning's guy the same rating as this evening's? Like giving the whole class an 'A' grade.