I can't comment about the US, but in the UK (and possibly on continental Europe) I think the insistence on people attending RCs or CAs in person is less about contributions now.
They're increasingly encouraging attendees to contribute online and electronically - in fact there have not been any cash donation points at assemblies and conventions here for some time now. This is because charities get an extra 25% called GiftAid from the UK government based on the tax status of the donor, which is easier to process and claim via electronic payments linked to the payee.
I suspect the push to get congregation members back in person is more about control than money. As several on this forum have admitted, it's far easier to put the Zoom meeting on in the background, keep your camera off and just do something else. No need to dress up and make any other effort either. To everyone else, you appear to be "attending" the meeting.
But to attend in person, you have to do all that's expected of you: smart suit or dress, pack your electronic device with JW apps, travel to the venue, sit down and follow the programme, meet and greet all the bros and sisters - and any attempt to step out of line is easily spotted.
The other factor influencing the insistence on returning in person is that other essential for JW life: appearance. The RCs and CAs have to look good, so the org can talk about how well-attended and "encouraging" it all is. Big gaps in seating and wide open spaces in aisles and concourses don't look so good!