Most people wait to get towed these days on those rare occasions that they get a flat tyre. In over forty years of driving I've only had three flats. One I changed the wheel, the second I just drove slowly for twenty miles because the tyre was at the end of its useful life anyway, the third was on a narrow rural road on a slope so in the winter in the dark so I just waited for the car to be taken away on the back of a lorry.
A lot of cars don't have a spare wheel now, why would they start carrying one in the future?
Back in the 1950s tires went flat often, so a spare that you knew how to put on was a must. These days tire technology is much better and so getting a flat is rare kit does happen of course, but it is not very common. Many cars will go through their entire life without using the spare even once. Since a spare takes up a lot of space and weight, it makes sense to get rid of it if it isn't needed much. Tow trucks have always existed, just call one to fix the tire when you have issues.
A lot of cars don't have a spare wheel now, why would they start carrying one in the future?