Both to and for can be used with liable, but they are used in very different circumstances.
Liable to is usually seen as part of the form liable + infinitive, and indicates what someone is likely or probable to do:
He is liable to want a beer with his dinner.
Liable for indicates someone has a debt, legal obligation, or responsibility:
Since he crashed my car, he is liable for the cost of repairs.
In your example sentence, both of them would use "for".
Edit: I've actually now found a number of example sentences in British English with "liable to" used in the sense of a legal obligation, just as with "liable for". So the first one may be acceptable either way in BrE - although as an AmE speaker, I would say that "liable for" is, at least on this side of the pond, the normal phrasing when discussing legal obligations.
Since the original sentence is British English (American English would not use "transportation" in that sense), I will defer to people with more knowledge of BrE on which they would prefer.