Elon Musk is wrong: Robotaxis are stupid. We need standardized rented autonomous tugs to move customized owned unpowered wagons.

Sorry for the flashy head­line, but I gen­uinely feel this might be the best idea I ever had.

After the in­ven­tion of the horse­less car­riage, it sup­pos­edly took peo­ple years to re­al­ize that with­out reins to hold, the driver could now sit in­side the cabin. Change of the core tech­nol­ogy al­lowed a re­think of the en­tire product (the ve­hi­cle) but that re­think was hard.

With au­tonomous cars, we already have a re­think. Au­tonomous ve­hi­cles can be called to a per­son who needs it, so they should not be owned (and sit idle while the owner doesn’t need to move) but should be taxis. Lots of peo­ple, in­clud­ing Elon Musk, agree that’s the way to go. And it is in­deed an im­prove­ment over the cur­rent car own­er­ship model. But it doesn’t go far enough.

The rob­o­taxi con­cept re­tains an out­dated as­sump­tion: that a sin­gle product, a sin­gle ve­hi­cle needs to do both the mov­ing and the ac­com­mo­da­tion of the user.

Get rid of that as­sump­tion and imag­ine in­stead a sys­tem made from two very differ­ent parts that can (au­to­mat­i­cally) cou­ple and un­cou­ple:

  • A driv­ing unit (tug) with the mo­tor, driv­ing and com­mu­ni­ca­tion sys­tems. This is usu­ally rented not owned.

  • An ac­com­mo­da­tion unit (wagon) for the hu­man(s) and their stuff. This is usu­ally owned not rented.

How is this bet­ter than rob­o­taxis? Lots of rea­sons!

  • Your per­sonal wagon can have a bed in it, or your valuables, or spare un­der­wear. You can use it as a mov­able locker, as you do ev­ery time you use a per­sonal car to get gro­ceries from mul­ti­ple shops. You can sleep in it.

  • Your per­sonal wagon gives you full con­trol over the space you oc­cupy while trav­el­ing. A rob­o­taxi re­quires you to take out your stuff ev­ery time you leave and check whether the pre­vi­ous user did ev­ery time you en­ter. And what if the pre­vi­ous oc­cu­pant used a per­fume you’re aller­gic to?

  • The tug doesn’t need seats, win­dows or air con­di­tion­ing. It doesn’t need to haul all that mass ev­ery time it is called to a new user. A lot of com­plex­ity is re­moved from pro­duc­tion, so these are much cheaper to build than rob­o­taxis.

  • Rent­ing out these tugs is much less has­sle than rent­ing out rob­o­taxis be­cause they need much less main­te­nance. They can be pretty thor­oughly pro­tected from in­terfer­ence by users. Charg­ing in­fras­truc­ture for tugs needs much less space than charg­ing in­fras­truc­ture for rob­o­taxis.

  • Your per­sonal wagon can be in a huge va­ri­ety of de­signs and sizes! Hu­man-pi­loted cars, and rob­o­taxis, are very hard to build and only make eco­nomic sense in huge num­bers, forc­ing stan­dard de­signs that are sub­op­ti­mal at spe­cial­ized tasks. Un­pow­ered wag­ons are much eas­ier to build, so small pro­duc­tion runs make sense. A small-ish com­pany could build spe­cial­ized wagon types like the self-driv­ing office, the mo­bile hair­dresser’s sa­lon or the Sparkly Uni­corn Car that takes your kid to school.

Now that I thought of it, I can’t un­see it. It seems blind­ingly ob­vi­ous this kind of sys­tem is much bet­ter than rob­o­taxis.

And the tech­ni­cal side wouldn’t be that hard to do. You need a stan­dard in­ter­face be­tween the two, the wagon needs to give the tug re­li­able info about its phys­i­cal prop­er­ties and maybe it’s worth think­ing about whether one of the two can make do with­out a bat­tery. No doubt I’m miss­ing some de­tails, but trains have sep­a­rated lo­co­mo­tives from wag­ons for a long time, it can’t be that hard.

There’s a bit of a chicken and egg prob­lem where you need to be sure the other part of the sys­tem will ex­ist be­fore you start pro­duc­ing your own side. But that seems solv­able with suffi­cient clout. If Tesla can in­deed demon­strate func­tion­ing rob­o­taxis, then Elon Musk say­ing they’re go­ing to build tugs (with an open source cou­pling in­ter­face) should be enough for lots of play­ers to start de­sign­ing wag­ons.

So I think it’s very doable. And the afore­men­tioned ad­van­tages over rob­o­taxis would help get rid of gasoline cars even faster than rob­o­taxis would. And that would help with global warm­ing. So we should all want this.

Am I wrong?