They are using stainless steel fermenters designed to handle carbonation pressures. They chill the beer and fill using low pressures.
There are similar tanks available for homebrewers. Buckets and carboys will not handle the pressure.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk