USAGE of 'were fined' is correct because, in the GIVEN sentence, the time reference is given i.e. 'last year' and the subject of the clause 'where' is 'pedestrians' so, we need to use the plural verb for this subject.Also, we need to use the PASSIVE voice because the doer of the verb 'fined' is SOMEBODY else.So the correct sentence is- A case in point is Sydney, Australia, where last year more than 8,000 pedestrians were fined for illegally crossing city streets.