The first point you're making I suspect alludes to wheelies and standies
I was thinking of the case where, in a car, the force between the road surface and the tyre is less than the friction limit given by (mu * r).
Consider, for example, how a rally car is driven along a track with a loose surface; it may spend the majority of its time in a condition where it has "lost traction", ie. there is relative motion between the road surface and the lowest point of the wheel. To assert that the driver is not in control, though, is plainly untrue.
Has it 'lost traction' or is it experiencing 'reduced traction'? If it has 'lost traction' inertia applies and control inputs will have no effect. If it has 'reduced traction' then control input will have a reduced effect. In the former no amount of compensation will allow for effective control, in the latter control is possible by compensating for the
reduced traction.
Perhaps others aren't taking such an absolutist view of the phase 'lost traction' as I am ("lost" = ?past perfect? = 'it has been lost'). If you think 'lost traction' includes 'reduced traction' or 'losing traction' ("losing" = ?present continuous? = 'it is being lost') then we're probably arguing at cross purposes.
[Errors of grammatical type naming are all my own, never could remember which was which; so much for a grammar school education, but at least it taught me where to use a semicolon.]
I have to make it clear that I'm most definitely talking about the physics of 'in control'. We're talking about autonomous vehicles and thereby control systems. So we're talking about when systems are 'controlled' (by a control loop, AI or driver) and 'uncontrolled' (the system is in the grip of inertia and external forces).
Your mention of 'legally' in control which reminded me of some prosecutions over wheelies and standies back in the day (mid eighties or nineties I think). You seem to be implying there have been cases around 'in control' and deliberate drifting? Frankly anybody who indulges in deliberate four wheel drifts on the public roads outside of a formal rally deserves to get prosecuted no matter how in control they are or are not in physical fact.
Can we get back to the actual case in point now, accident avoidance by autonomous vehicles (with a side helping of accident avoidance by humans). I'm conscious of having side-tracked this thread too far. I'm not going to indulge in any more commenting on this side issue.