I live in South Australia, and- in the circles I move in anyway- it is not the norm to remove your shoes when visiting someone. I've only been to one or two homes in my life where people have done this- they had shoes by the door, so we did it out of respect, but it was unusual.
I often don't wear shoes at home, for comfort more than anything. Neither does my son. My husband wears shoes most of the time, once he's fully dressed and ready for the day. But when we visit someone, it would only be in houses where we felt really at home that I would take my shoes off, and I doubt my husband would anywhere else... he'd just feel too uncomfortable. My son often does with friends or relatives... as kids do. But even he wouldn't at the home of someone we didn't know well. I think most people would be taken aback if we took our shoes off... think it was weird and a bit "off colour".
I agree and understand the idea behind it though... I'd love to not have stuff walked in on my floor! The hygiene isn't as much a problem as the grit, these days, as my son is 13 years old, and not crawling as much as he once did.
However, we have a housemate who lives with us and I would not
want him to take his shoes off!!! He has atrocious foot odour, and his jogger type shoes make his socks/feet stink even later on on a day he has a shower. So I'd much rather have them covered!!
We have hardwood polished floors, but don't seem to have much of a problem with marks on the floor from shoes, dogs, or anything. We all just basically wear joggers or flat shoes in our household anyway. And we don't have a lot of visitors, and those we do have don't generally wear high heels either just to visit us.
If I ever did think we'd be better off with a "no shoes policy" I'd never ask a guest to take them off though. I realise most would be very uncomfortable with the idea. I'd just leave an obvious pile by the door and leave it up to them. (I would ask them not to smoke though, however I don't think many people would here these days when they visit our home- not without asking first. This is a strong enough issue for me to do this, while shoes would not be.)