Is it normal to wear formal wear into simple stores in other countries?
The question really is “what constitutes formal in this context?” Prom dress in a Walmart is unusual. A high power business suit would not receive odd looks though it is, in its own way, quite formal. If you distinguish between formal daywear and evening wear, you’ll find that formal daywear gets fewer odd looks, just about anywhere. That said, casual wear is more the norm in Mexico and the tropics, more conservative or “day formal” is more the norm in England.