I didn't assume Shatner wore a full cap. I'm not sure Elton John does either.
I hadn't seen him w/ an exposed hairline - only "bangs." He has the money to color match to his & get pieces that match the hair he has.
Why is cetain that Elton John wears a full cap?
He's gone on record, like Shatner, as saying he tried plugs & they failed badly...