It’s worth noting that the two-wheeler demonstrated in this video is an old-style one with wheels just attached at the box. The Butchers and Bicycles one linked by the grandparent post is one with an actual steering at the front - the box and the bike will lean into a corner, just like a two-wheeler would.

This makes modern 3-wheelers much more agile. They still have certain disadvantages- they’re wide and bulky, you’ll have trouble avoiding potholes etc., but they’re nowhere as bad as those boxes with wheels (tough you can still buy those - their upside is their low price)