In North America, we don’t expect public toilets mostly in malls, highway rest areas, municipal buildings, and coffee shops/restaurants. In larger cities you could drift through a large hotel looking confident, but for now COVID has ended that.
But many countries, especially in places with lots of tourists, actually acknowledge that everyone needs a toilet once in a while. They put large, clean toilets in obvious places. In Taiwan and Tokyo we were pleased to see them in all the medium-or-larger stations.
ALWAYS HAVE SOME LOCAL COINS. Quite a few cities’ toilets have an attendant who expects a tip, and others have a coin-operated turnstile. What they do NOT have is a change machine nearby.
Google Maps (the regular one, not MyMaps) is often good, Put a place into the search box, and after the map displays, click on “Nearby” in the strip at the left side. A cursor will appear in the search box at the top of that left strip. Type “toilet” (“WC” also works in many countries ) and if Google knows of any near the current place it will display them.
Phone apps: If you Google for “toilet finder app” you’ll find several apps that help you locate what you need, including WC-Finder, Flush Pro, Toilet Finder, Public Toilet Finder, SitOrSquat, WhereToWee, and Bathroom Scout. You can also find specific apps for countries and cities.
Here in North America, public buildings such as city hall, libraries, shopping malls, etc. usually have a washroom that the public can use. Just walk in like you know what you’re doing and you’ll usually spot it.
Large hotels used to be a good choice, but with COVID-19 many have closed their main-floor toilets. Ditto for supermarkets. Department stores used to be good, and some still are. But you may have to go to the sixth floor, knees pressed together the whole way, then try to find the poorly-marked entrance.
Coffee shops etc. are increasingly expecting you to buy SOMEthing, and that’s not unreasonable, especially if they are cleaning more frequently these days. In busy tourist cities they definitely expect this. But in Italy, for example, you can get an espresso for €1, and sometimes you’d cheerfully pay that just for the toilet.
If you’re running out of time, though, a high-volume high-turnover place like McDonalds isn’t going to bother with washroom keys or codes. And if they do, you can always hover till someone comes out.
Key tip: Think of the old Stevie Winwood song: “While you see a chance, take it.”