Doesn't Lyft work sorta like that? Idk, it doesn't operate in my country, but from what I've seen online, it's several strangers sharing one ride.
But after giving it more thought, I tend to agree with you on this. Except... After posting my comment I got curious and decided to calculate the efficiency of cars vs busses. I always assumed that they were way more efficient than cars (cause lugging around 2 tons of steel just to move 1 or a couple 70kg hairlines apes is stupid). But it turns out that busses only win if we compare it to cars with only one passengers. So basically, at half load, both are about equally efficient (about 10%). And on average a bus is only half full. Turns out, busses are really heavy... there's of course the density, and busses win if you give each passenger their own car, ~~but if we pack cars fully, they will be significantly more efficient~~. Not to mention if you use smaller European cars that carry basically their own weight in passengers.
So my conclusion is, to maximize efficiency in the future we should try to implement a system of highly packed smaller sized transportation devices.
Edit: I did some more calculations and now disagree with my own conclusion. Busses still win even when cars are reasonable utilized, not to mention the usual utilization, which is 1.2 passengers.
More details in this comment.
Because trams and busses can't fulfill every need. Certain point to point transportation options still need to exist, we just need to make them as efficient as possible.
And as I mentioned in another comment, ~~turns out busses aren't really as efficient as I thought they were. Fully packed small cars are way more efficient~~.
Edit: Changed my mind. See previous comment.