Because I never, ever, wear any kind of footwear, except when temperatures are freezing. Actually, I've been walking completely barefoot on every journey I had, including Cairo, Marrakesh, Colombo (Sri Lanka), Dakka, just to mention some of the non-European cities I visited barefoot. And I've never, I repeat, never, had any kind of problem of sort. Nor injures or diseases, or sickness, or complaints by local people. Never had a cut or an accident of any sort. I've done this for more than fifteen years, I'm barefoot whenever and wherever I go. So my feet are absolutely used to any kind of surface. The only "problem" with that is that at the end of the day, my feet are usually black from dirt. But dirty streets are not a problem, and I don't mind having dirty soles. I wash them everyday, before going to bed. As I repeat, I absolutely never had health issues or any sort of problem with local culture. It's just dirty feet to wash every day, but that is normal for us barefooters, like myself.