I really don't care if people wear shoes in the house ... the point of carpets and flooring is to be walked on, surely? If they can't cope with people tracking a bit of dirt on, then they're really not fit for purpose.
I don't wear shoes in the house and am barefoot most of the time but that's purely because I hate wearing shoes (and socks), to the point that if I have to nip into the back yard/to the neighbour (I live in a terrace) and it's a nice day, I have been known to forego them. I have been like this since I was a child, my parents used to have to bribe me to put my shoes on, and I'd still kick them off at any opportunity. Occasionally I will wear slippers, but thats only because I have slate flooring in my kitchen and tiles in bathroom and in winter, even with the heating on, they're freezing so I do it for practicality.
I live in a rural town but not once have I had people track crap into my house - but then most guests have the common sense to know "Oh, we've just been on a woodland walk in the rain and my shoes are really muddy, lets take them off at the door" or "We've been for a walk around town and we've not stepped in any visible mud/dirt, we'll just give our shoes a good wipe on the doormat". And if, after someone has visited, I notice it's particularly dirty, I just hoover it like I hoover most days anyway!
The entrance to my house is tiny - I live in a two up/two down terrace - and there's literally a square "hallway" just big enough for the front door to open before you're at the door in to my living room, and both of those areas are carpeted, so to remove shoes before you step on my carpet would require people to literally stand in the street to remove shoes, or stand in the open doorway (can't close the front door since you're in the way and only way to be out of the way is to step into the living room) on the "hall" carpet to remove their shoes before they stand on the exact same carpet in my living room ... hardly a welcoming entrance for guests, especially on bad weather days!
I would rather guests be comfortable than constantly being concious of mismatched/holey socks or smelly feet and anyone who comes into my house is more than welcome to wear shoes or not, as I care more for their visit than for my carpets!