we haven't even managed to get main line driverless trains yet, and that only needs fairly simple speed control in one dimension. making trains obey signals is a trivial exercise, as anyone with a model railway and a modicum of electronic background will know.
so if we can't effectively control an electric motor autonomously, i think aircraft are safe for a while yet.
given how easy automatic trains should be, there must be a good reason they don't do it. public opinion.
docklands light railway or the train at Stanstead just trundle so don't count