Technofreak:
This rukus from EV and PHEV owners about the issue with the online RUC purchases insinuating it's all to do with the wave of RUC purchases from EV owners shows to me how totally wrapped up EV owners are in their world.
Have a look around and take note of how many vehicles there are on our roads that require RUCs and then think about how that number compares to EV numbers.
A lot of cars, SUVs etc are diesel and pretty well any thing bigger than a Ute is a diesel.
There are 818,324 Light diesel vehicles (2020 data), and about 150,000 heavy vehicles (which, other than electric which is exempt until December 31, 2025 pay RUC regardless of fuel).
Lets assume on average they by RUC's twice a year (noting much of the heavy fleet don't buy through the regular system using an eroad or similar instead, and for light vehicles the transaction fees are a decent chunk so people tend to buy larger blocks), and it is evenly distributed across the year. That works out to 37,000 transactions a week.
There are approximately 107,000 Light EV's & PHEV's in the fleet. lets assume half of them buy RUC in the last 7 days of the amnesty period. that's 53,500 Transactions in a week (on top of the regular 37,000 transactions). So about 244% of regular demand. That's enough to stress most system's.