[gambiting]

I don't know about that specific model of Volvo, but the emergency brake works up to much higher speeds in other cars/brands - it's just that above 50km/h it's not guaranteed to slow down to zero or prevent impact, just reduce the speed. I suspect that system was disabled as it would interfere with whatever driving tech tech have though.

[TrickyRick]

In Volvos case the system is called City Safety and is only active up to 50 km/h (https://en.m.wikipedia.org/wiki/City_safety)

However there might be other systems which break automatically for cars, in the case of a sudden traffic jam for instance.