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There's just no need for through-axles on a cargo bike... I also find tyre clearance perfectly adequate (I run a 32c on the rear, and you could go bigger by changing the mudguard), although to be fair I have a 406 wheel on the front, not a stock 451 (1.5'' tyre).
Vertical dropouts at the rear limits the options a little, but a derailleur is actually often the best option, since Alfine and Nexus hubs are not very well sealed.
As for the price, it's a niche bike, made in small numbers.
Lolo-
Surely through-axles would enable more secure stopping power when fully loaded? Not that I'm not super happy with my Mini Max, I've just often wondered if it might help.
I would also add @LeMesjeu Omnium's are very well finished frames, particular details like the drop outs look much better in the flesh than most photos. Plus if you speak to your local dealer they may be able to work with you on price if you do the full build with them
VeloSurMer
The Bogbi is targeted more as a "family hauler" that also happens to do cargo, or that is what they stated in the mail they sent me. Which is probably marketing speak for, it will cost boatloads of cash.
The omnium is still a nice bike, but the design needs some updating to modern-ish standards.