Three wheeled cars and trikes mostly moved to having the two wheels in front for stability when cornering. Same reason why 3 wheeled all terrain vehicles were taken off the market. Otherwise, cool idea.
We now ride a two wheeled urban arrow. Three wheelers seem incredibly unstable except perhaps for ones with independently pivoting wheels like the babboe carve
Perhaps I should add to this that they're actually super stable at slow speeds, compared to two-wheelers, especially when loaded. My wife prefers a cargo bike to her usual non-cargo bike, I think for this very reason.
I really can’t tell, are you referring to an F-350 or a cargo bike?
Babboe is a rather budget brand that uses a single round lower tube under the box. Compare that with the frame of an urban arrow or a R&M load that use multiple tubes and a proper stiff platform under the box. Even if an Urban Arrow Frame would crack, it would bend out of shape instead of failing catastrophically like the Babboe did.
Obligatory Top Gear link: https://www.youtube.com/watch?v=QQh56geU0X8
“You may remember: I drove it (the Reliant Robin) around Sheffield and it kept falling over. Well now’s the time to come clean. A normal Reliant Robin will not roll unless a drunken rugby team is on hand. Or its windy. But in a headlong drive to amuse and entertain, I’d asked the backroom boys to play around with the differential so that the poor thing rolled over every time I turned the steering wheel”