This is very manipulative picture, although not as bad as the famous Munster photo (this: https://headwatersolver.files.wordpress.com/2013/08/64408578... notice how each photo has different perspective and zoom to make cars appear the biggest and bicycles the smallest).

When I need to get to the work, pick up groceries, transport two 30-inch displays across the town, etc., I simply do not walk out to the street, pose for a photo, smile, camera flash and go back to the building.

Transporting somewhere in terms of congestion is 'space integrated over time'.

First and obvious nitpick - there is single person in each car and absolutely no cargo.

Then, if it really worked like the picture suggest, the tram would need to:
a) transport each person directly between their endpoints,
b) do it in the same time as a car would do,
c) be full to its capacity all the time.

Given all these conditions, the cars in the picture (disregarding the single person occupancy and cargo) would really equal to the single tram.

But that is not the case:

a),b) In a car one can drive the shortest/fastest route between his desired endpoints, in the tram/bus one needs to follow the lines. There simply cannot be a complete graph of public transport lines going from every possible start to every possible destination, so you need to run up some extra distance to a 'hub' and switch lines, adding time. And even if there is a direct line, it typically goes as it can serve more people. One example, suppose you have a city with predominantly commercial and industrial parts in the centre with majority of the jobs and predominantly living parts in a star shaped pattern on the outskirts. If you happen to travel from one living neighbourhood to another (e.g. you work there, you are visiting a girlfriend, sport venue), the public transport will take you through many many stops around the centre, while in individual transport you can go between the quarters directly skipping the center completely and getting there a lot faster. There simply isn't enough people to fill a tram/bus between non-major stops in a reasonable intervals.

c) Unless you have 100 % mixed jobs, industry, commerce, leisure, education, everything on each stop and unless you have this with perfectly balanced population density end-to-end, you won't have fully occupied vehicle.
In order for that picture to be true, the tram would need to fill itself on its very first stop and on each stop, equal pax would need to enter/leave. Fiction.
I live at the end of the tram line and in order to get my seat in the happy photo of a full tram in the picture, then the tram must first arrive almost completely empty (in the morning, everyone goes from this living neighbourhood to the jobs in the centre and back in the afternoon, reverse flows are minimal) to pick me up. Then, the tram continues quarter- to half-full for several stops until it really have at least [# of seats] pax onboard.

To sum up:
I) tram takes twice the time because I have to route around with the majority of the flow instead of going direct route,
II) it has to arrive almost empty to pick me up,
III) it isn't full to [# of seats] for significant part of the journey.

So for me as a single person, count not one, but 4 to 6 seats to achieve the same 'space over time' density.
If I pick up my colleague on the go or drop him of, count approx. 8 seats. Two colleagues, 10 seats.

Suddenly if all the cars in the picture doesn't conveniently fit into a single tram, but in several of them spaced apart, it isn't so nice propaganda...

PS: I lived in a socialistic east-bloc non-SSSR country. In order to have a car, you had to be privileged/bribe/camp on the waiting list (literally camp in front of the state-owned car dealership). The public transport was wonderful, there were railway tracks going to every forgotten small village, bus lines everywhere, intracity transport roared through empty streets. The catch? Be any small fraction different that the 'major' flow - morning shift, evening shift, night shift interchanges between industrial jobs/housing areas/villages and you are out of luck, you either got blackmarketed a car in any possible way (e.g. train drivers), drive bike through the harshest freezing conditions or go with the flow and forgo anything else than 'buy groceries at corner store' (with regulated flat prices regardless whether it is 500-ish person village or capital city), 'go to job early morning', 'return from job in the evening' (nevermind that job was compulsory). Think Venezuela in recent HN.

Making using a car more and more miserable without improving public transport is, in reality, beating everybody into the averageness of 'you need to go from this stop to this stop at this time', otherwise sit at home or in walking distance. I been there, seen the carless variant and the free carsupported variant and it is a lot better even if you have to sit out through a traffic jam.

TL;DR: The public transport excels at only one thing - very major traffic flows in peak hours. Sucks very much at everything else. Self-driving car can be a nice hybrid - offering full occupancy of vehicles traveling at minimal distances between them (coordinated braking) in peak times, while still functioning nicely outside of major flows and allowing complete freedom outside of the peak hours.