Wonder if they just have a bunch of cheap chromebooks that they use to keep everything separated.
It can be done easily with each user having his own browser (Chrome, FFox, Edge, Brave, Opera, ...) on the same machine
or, for clearer difference and avoiding surprises, with separate virtual machines installed for each.
That part is the least problem imho.
(However, I'm still shocked about these findings, since we don't talk here about the usual shitposters).
You read my mind. A virtual machine with different profiles is quite convenient to understand in which machine which account. Well, if we take into account the experience and attentiveness, then one Firefox with 5-10 profiles is enough.
Here all the relish lies in the fact that he did an excellent job in his job.