bambina, yes that's true .. if your (under3) child takes a seat, then you must pay. if they're under 3 adn on your lap, then they should not pay. only know this as we had a fight with a minibus driver once who tried to force our maid to pay for our (then 2.5yro) son even tho he was on her knee. Had to phone all kinds of places (Minibus association, transport dept, police) to check. tehy all confirmed for minibus it's 3+ unless the child takes a seat. --of course, never got an appology from bus compayn
Double deckers / big bus is usually 4yrs. Not sure on train, as once son turned 3 we just bought him his own octopus and he travels with that ... in the grand scheme of things, it's only a few dollars for the kids - - - trust me!! better than getting into a yelling match with an irrate bus driver (i know - i've been there -- and it ain't fun!)