A great strategy but has its limits. Just a few weeks ago some guys tried a rather good version of this strategy in Estonia to sneak into a Rammstein concert. Not only did they have high-vis vests, but one of them also had high-vis pants, both of them had working gloves and they were carrying a ladder. [1]
It didn't work out though, they didn't get past security. I think one of the major flaws in their attempt was that they arrived too late, thousands of regular people were already on the premises. They should have come early in the morning.
Never mind that most stage hands wear exclusively black, not high-viz. A concert is probably one of the few places where seeing someone in a high-viz outfit stands out.
I used to live and socialise in a place where a lot of my city's security guards and bouncers drank, and became if not friends, at least familiar with many of them. (Kings Cross in Sydney in the 80s/90s)
I also used to pretty much exclusively wear black jeans, black t-shirts and when it was cold enough a black leather bike jacket.
I would often show up to clubs or gigs, and just get waved in by whoever was on the door because that assumed I was arriving for work.
It was the middle part between the two bits you quoted - he was just going to a show, was in a phase where he liked wearing all black, and would get waved in without even intentionally trying to trick anyone because they assumed he was arriving for work. Does that help?
Yeah. These would all have been "show up and pay at the door" type places, not sold out weeks in advance with pre-booked tickets. Bouncer (or sometimes door bitch) takes your money, unless the bouncer waves you through.