The EU and the Aussies most likely have better infrastructure and make their cities walkable compared to the USA.
Australian cities, like the US, are built around the car. In the old days when a lot of people didn't have cars, and there was also a stronger Christian base, there were local churches where people could walk, in cities anyway.
But these days most people have a car (with rising fuel prices to boot) and the rate of church going has dropped considerably.
Secondly most public transport is designed to go into the city centre and then out again. That's fine if the church happens to be located near a suitable transport hub (I'm thinking of one Catholic Church that backs onto a railway station when I say that), but that's rare except for inner city churches.
Unfortunately as my old pastor said to me once "If you know anything about church building, inner city church building is deadly. If you want to build a big church you go to the outer suburbs where the young families are". Young families in outer suburbs usually have cars, often more than one.
I suppose our parish is outer suburban verging on rural. We have three Catholic churches which keeps the single priest very busy. The closest one to me is about 5 kilometres, the next about 8 kilometres and the furthest (which I often attend) is about 20 kilometres. And, yes, I drive.
Our current priest is moving to another parish soon, and we'll be gaining a Nigerian priest who I just happened to meet today. He seems like a good bloke.
The Nigerian priest's current parish is based in a town called Childers and there are apparently five mass centres, including Childers itself. It's a 55km drive to one, 107 to the second, 46 to the third and about 38 to the fourth. That's to say nothing of pastoral visits. He does a lot of driving. So does the archbishop when he has to drive to Childers from Brisbane (about 312 kms).
It's all centred around the car these days, like the US and the West in general. We're very materialistic which is another reason Christianity is declining - we're too well off.
Our materialism reminds me of a story a friend of ours told me when he was doing some door knocking for his church. It was a hot, humid day and he was sweating and not having much luck. He came to one home and there was a bloke sitting next to a swimming pool, sucking on a stubby (short beer bottle) and looking much cooler than the door-knocker. In the driveway was a four wheel drive and next to it an expensive boat on a trailer.
The bloke said "What can I do for you?" Our friend looked around, mopped his brow and said "I'm here because I'm supposed to be telling you what you're missing out on!"
The bloke laughed. He was polite and they had a conversation but he wasn't interested. As he saw it, alll was well with the world.