English Language Tests, Intermediate level
ESL/EFL Test #881 [color=blue]“Taxi Terms”, question 10
Is tipping a taxi driver … in your country?
(a) congruent
(b) customary
(c) colloquial
(d) consecutive
English Language Tests, Intermediate level
ESL/EFL Test #881 [color=blue]“Taxi Terms”, answer 10
Is tipping a taxi driver customary in your country?
Correct answer: (b) customary
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I think it should be “Is tipped a taxi driver…”, isn’t it?
No.
It should be ‘tipping’.
It refers to the act of giving a tip (so is a noun) - tipping.
Incidentally, your question tag is wrong.
You started the sentence:
“I think it should be…”
so the tag should be
“shouldn’t it?”
No, you have to use the “-ing” form of the verb, because it acts as a noun. The “-ed” form of a verb cannot act as a noun.
PS: Bev, when I started writing my reply your reply was nowhere in evidence, sorry. 
Heh, confirmation is always good, Tort! No need to apologise – especially when the posting times are so close together that it’s obvious what happened.
Thank you both XD