It's been quite a few years since I last worked in live show production, but on any show at a venue where we couldn't be sure of access to clean power, humbuckers (not the guitar pickups, a nickname for what I believe was just a dumb 60hz notch filter or ground loop isolator inlined on house power taps) were a standard pack out in the road kit.
I would have expected that this decades-old and well established component of power infrastructure would have been commoditized by now and integrated into any dedicated AV performance/production space such as an auditorium.
> what I believe was just a dumb 60hz notch filter
A simple notch filter won't fix 60 Hz hum. Or, at least, when I've tried to eliminate annoying 60 Hz hum in my own amateur recordings, it's never been very effective. The problem is that the 60 Hz hum isn't a sine wave. It's more like a square, so you've got a bunch of harmonics up the frequency spectrum to worry about too. You can try to also notch out 120, 180, 240, etc. but it starts to get weird sounding fast.
I can confirm this from experience. In addition if there are any professional sound engineers involved it's likely a coincidence due to lack of funding.
I would have expected that this decades-old and well established component of power infrastructure would have been commoditized by now and integrated into any dedicated AV performance/production space such as an auditorium.