Many (most?) are hosting web applications and/or content in separate applications and sometimes servers from where TLS (HTTPS) termination happens. HAProxy, Traefik, Caddy and Nginx as reverse proxy and TLS termination servers are pretty common, even more so if you're containerizing your applications themselves. It dramatically simplifies the application stack.

While I may make the argument that most are probably hosting and doing php on the same server, it's not the typical approach for any custom software at this point.