All fair, I think that's part of the problem lockdown is fine this time time round and the economies of the world are taking a huge dent. We are having a worldwide enforced 10 day furlough (actually EMEA its voluntary due to nature of our contracts) but that is opposed to letting masses of employee go. We can probably take the brunt of it this time around provided the likes of Boeing and Airbus survive through it. If the next one of these occurs next year there's no way the economy can take that. If its a once in a generation thing you can probably react the same way in terms of stimulus but this is unpredictable and doesn't occur like clockwork.
Testing like you say can be important in implementing a mini lockdown and isolating carriers before it become a problem. You can't just stop flights because again major impacts, how do you test people coming in, for a new virus how long does testing take? Do we even have budgetary means to ramp up testing in time to even make that feasable?
And this is kinda my point, we are currently in a crisis and whilst we should definitely look at things with a critical eye we can't properly assess what went wrong, what went right, what do we next time until its over. The simple reason for that is the people with the actual know-how are on the front line currently so any proper asessment can't be done in real time.