Firstly, like you, I'm not arguing, just pointing out inaccuracies of claims being made.
Yes, both FCL and RIAT are 3-day events, and it should be no surprise that they are Friday, Saturday and Sunday and as Friday is a workday it will be the least supported day, that's logical.
Its around the 150 mile trip for me to RIAT and unless I have something like your Tesla which for reasons already explained, would not be the case (£53k) so would possibly need to charge on the way there and again on the way back if I had a car like @Rootedmini, that would be the case. I already have to leave home at about 4:00am to get there just after the gates open.
I certainly would not want to leave any earlier, or indeed stop for a charge on the way home as it is already quite late in the night by the time we get home. Compare that with my current car, I know I fill up the tank the night before, and I'm good for 600 - 700 miles so no need for stopping on the way home, once we have got off the base.
So if we can only get tickets for the Sunday, not a problem with the range either as the following morning, I have to do another trip of 30+ miles taking my son to work for his 7:30am start.
I also know from talking to other people at the show that they have driven down on the day from places like Manchester, Newcastle, Norwich etc and if they were driving an electric car could also be seeking somewhere close by to grab a charge, and this is just going to get worse as more electric cars are brought each year upto 2035, when all new cars will be electric. But hopefully by that time, the range will be greater and cars will be more affordable. If I was still working, it would be a Tesla sitting outside my house as it is a no brainer when the BIK is considered and that someone else is paying for the car and savings made on fuel costs would offset the BIK tax.