You must be lucky. My cellphone carrier used to injects scripts and ads on plain http requests. Imagine seeing ads on wikipedia. Now that https is everywhere, this behavior is largely stop.
Are you sure about seeing ads Wikipedia? AFAIK Wikipedia itself doesn't run any ads [1] (except occasional call for donation), so the ads must've come from other source (e.g malicious extensions, malwares that install mitm proxy to inject ads, etc).
