> Why is that the bar? It they are safe and useful in other situations, they can already be used in those other situations, no?

Unlike in SW, choosing a different path might lead to accidents.

My car can keep the lane very good in a sunny day, when the sin shines from above (i.e. midday).

In heavy rain or snow, i can rely only on my senses.

For an automatic driving car to be useful, it must function correctly in 100 % of the cases (ok, 99,999 %).

I was talking about general purpose autonomous driving. Special cases of autonomous driving have been in use for a while like trains (the Yurikamome in Tokyo started operation in 1995), buses driving on designated routes, Waymo cars that operated in certain areas etc.