Lazurii, I'm sure someone else will chime in with some 'liability issues' suggestions, but on the topic of 'carrying shoes', there are easily found little shoes, similar to ballet slippers (slippers, not the toe-shoes!), and they fold up very small & usually have a little matching pouch. They are sold as something to throw in your tiny purse or pocket when you go out clubbing, so when the night is over & you're on your way home (and presumably drunk ;) ) you can slide them on for comfort instead of tottering around on your impractical high heels. Heh. I just like 'em because they're very small & can easily be stowed in your bag.
I saw a bunch for sale at (I think) H&M in a bin near the registers for $5. I've seen them in other stores as well & they're usually inexpensive.
Anyway, that could be an option for you, in places that give you a hard time. There's also, of course, the 'foot jewelry', which can make it appear to people that you're wearing some kind of thong-style sandal. There are links to them somewhere in this thread, or you can even make some pretty easy with some leather lacing, or maybe make a strap with a few layers of embroidery floss/thin yarn (macrame it up for durability) and wrap that around your foot. :)
Here are some links:
http://www.barefootsandals.com/ < -- This is what some of them look like; they're basically foot jewelry. You can make your own using theirs as a guide, with stretchy beading cord & beads. Or you could crochet a chain & tie it around in a similar manner, or make a 'friendship bracelet' with macrame & tie that around. There's another method for tying that I'm searching for...the one I want to find look more like Birkenstock/Teva style sandal-tops. Hrphm.
http://www.instructables.com/id/Tatted-Barefoot-Sandals/ <-- These are pretty if you can tat (I don't know how), or you could use it as a guide for making a similar version in crochet or maybe knitted?
http://www.ehow.com/how_5064589_make-beaded-barefoot-sandals.html <-- some instructions for making them in the style of the first link
ETA: Here we go! It was in the first post of this thread. Heh. In the Barefooters FAQ. :) http://www.barefooters.org/faq/22.html
Since the 'foot jewelry' style thongs are somewhat popular on the beach, some people might realize that you're not wearing shoes. The link above has a version that looks a bit more 'realistic' and should get you by most of the whiners. ;)
Who knows, maybe the kids will find them cute and/or comfortable & also wear them, then you don't have to worry about shoving shoes on them when you want to go inside stores! :)
EATA: Oh yeah, the Barefooters FAQ ( http://www.barefooters.org ) probably has answers to your other questions, now that I think about it. :) Like, is it legal to drive barefoot? (yes, in all 50 states, as well as Canada & England!) Also, I think the 'rules' that some food establishments try to trot out (OSHA, etc) is only for EMPLOYEES; there ARE no regulations for CUSTOMERS. The Society for Barefooters page has all the info available. :)
Edited by Brendalee - 7/10/11 at 10:29am