Not consistently. This is a critical part of URLs. Not displaying it is like not displaying zip codes in US addresses (I recently lived at an address that differed from a nearby address in zip code only. We were constantly returning misdirected mail to each other.).

It (https) is displayed consistently in Chrome's address bar though. I agree that the scheme is a critical part of a url. The question is whether a real url must always be shown in the address bar.