It looks like they popped the top off and rolled it under the cabinet. I don't think adjustable feet were an option for these.
Not only is it 1/2" wider than an actual built-in, it also projects out about an inch extra and unlike a builtin there is no room in the back for pipes or wires as that would cause it to stick out even further.
And look at the kick space. Instead of the toe space that base cabinets have, one actually has the opposite with the machine sticking out a bit at the base.
We had friends who bought a portable mid-line harvest gold kenmore in 1977, then built a house in 1981 and wanted to build it in.
She later pointed out these disadvantages