This is stupid, I wouldn't reveal my password to any customs officer. They should refuse and file a complaint instead of agreeing to these searches, especially if people aren't legally obliged to do so.
I'm living in the EU and I've never been asked for passwords. Usually if you have a laptop you are asked to turn it on, but that's it.
True, also in the EU and all you have to do is prove that it's a real phone by leaving it on. Phone searches are a ridiculous invasion of privacy, although fortunately Bitcoin isn't illegal in itself so if people take caution with their computers e.g. not having Tor installed or uninstalling it if they have it, they should be pretty safe. It may even be reasonable to file complaints just out of principle rather than out of fear of getting caught anywhere.