Some could be because of a culture of 'free travel' on trams, due to the low likelihood of being caught without a ticket. Or it could be just plain laziness. Another explanation is that from the passenger's perspective, validating achieves nothing if the passenger is holding a current two hour, daily or weekly ticket. The failure to validate in this case cannot be regarded as fare-dodging, as it makes no difference to the total fare paid. This is because records from validators are used to measure ridership per company for the apportionment of fare revenue collected through Metcards.
More validations mean more revenue.
Companies also say that patronage data collected through validations is useful for planning purposes. Though various inducements may be offered, these are little cheaper than the equivalent Metcard, and allow travel only on routes operated by the company concerned. These tickets are generally poor value for money, and their use undermines uniform ticketing and encourages the return to a fragmented ticketing system as operated before 1983. Their only aim appears to be to generate more revenue for the company concerned. This works because whereas Metcard revenue is shared between all bus, tram and train companies, single-company tickets benefit only the company that sells them.