How can all of those tested be hospitalised? If most of the tests are negative?
If you've been watching the figures from the start you'll realise that the ratio between overall number tested and the number of positive cases has increased.
To start with they were contact tracing and testing which mostly resulted in negatives, now they are predominantly testing anyone admitted to hospital from pregnant women to dog bites.
Since the argument was that they were only testing serious covid-19 cases and the only place testing on any significant level is in hospital this would if true equate to a much higher hospitalisation rate than 10%.
The hospitalisation rate is based on projected community transmission rates, they may not be entirely accurate but data from China, Italy, Spain and France seems to back that up. These are overall infected/hospitalised rates not based purely on positive testing.
If you think about it logically 33,718 have tested positive, if only 10% of that number had been hospitalised that would be roughly 3,300 since the beginning of this outbreak in hospital, we've had 2,921 deaths so unless this virus killed almost everyone who ended up in hospital the percentage of those who test positive and end up in hospital must be much higher than 10%, the only way to get that is to only test those admitted to hospital unless it's much worse than we think.