There's a bunch of reasons, probably starting with the voting there being so much more complicated - there are a lot more positions being elected than in the UK. It's hard to say if the machines are really cheaper, but there seems to also be a lack of willingness to adequately fund the process, judging by the queues in many places.

Which is a shame, because it's a fairly effective way to push money back into the economy, at least when a manual system is used.