I used to ride my bike to TAFE college (I'd have to take the bus that leaves an hour before class and it was only a few kilometres from home). My knees are kind of fucked now, and work is 30km away, so I have to put up with dickheads who are eligible for a refund on their license.
I did bike every day from Best to Eindhoven (both in the Netherlands). That's about 10k's a trip. But now, from Charleroi to Namur, that's about 42k's and a bit too far for my likings.
Besides, the landscape in NL is pretty flat, which makes it easier to bike, but here in Belgium (Wallonia), there are more hills, and I'm still riding a "Dutch Granny bike".
No probs with my knees though. Or I do not know it yet!
And public transport in Belgium... is better organised than in Australia, without a doubt, but best? Nah!