Up to that point, the UK was an exception rather than the norm in terms of cross-border travel. Quarantine is mandated on arrivals from abroad pretty much everywhere else in Europe. Austria is leading the way for now by allowing the quarantine to be replaced by a negative test, done either at VIE airport at the eye-watering cost of €190 or at an independent lab before the trip for one third of that cost.
It's another matter how timely such a measure is or whether imported cases are the biggest problem while the virus is running rampant across the local population. And, obviously, its introduction will smash up most of the efforts to start restoring some degree of connectivity by now.