I'm guessing there is some subtext here that an armchair analyst isn't going to catch from reading just this paper. Perhaps, for example, the cost of asymptomatic cases is there because "asymptomatic" doesn't actually mean "no symptoms at all", it means "the patient didn't subjectively feel ill enough to seek care." In which case there probably is some real cost to factor into the average. Or perhaps the argument is that asymptomatic cases still carry some risk of secondary effects such as myocarditis that absolutely need to be taken into account and averaged into the group from a public health perspective.
It's hard to say for sure, since the paper clearly isn't written for a non-expert audience and therefore doesn't spend much time on defining jargon.
Compare the experience of reading one of Einstein's scientific papers with the experience of listening to one of his interviews. It's almost like they're not even the same person.
The authors thoroughly outline their approach (and its limitations) based on available literature.
What specific criticism do you have?
When measuring economic impact, they could very well be equivalent. A dollar lost when someone can't work due to a broken bone is economically equivalent to a dollar lost when someone bedridden with a virus.
Best case, your comment is an oversimplification of what the authors spent a dozen or so pages explaining. The limitations they describe perhaps encompass some of your concern. They also describe alternative calculations.
"We first use the Department of Transportation (2016) guidance on value per statistical life (VSL) and severity/injury estimates as a basis for our non-fatal valuations by category. After updating the figures for earnings and inflation the DOT guidance recommends using a VSL of about $11 million in 2019 dollars. We use the severity classifications in the DOT guidance as a basis for our non-fatal valuations. DOT (2016) recommends using six different severity categories in benefit-cost analyses including Level 1 (minor), which corresponds to using a 0.3 percent amount of the VSL, Level 2 (moderate), which uses about a 5 percent amount,Level 3 (serious), which uses about a10 percent amount,Level 4 (severe), which uses about a 27 percent amount fraction,Level 5 (critical), which uses about a 59 percent amount,and Level 6 (unsurvivable) which uses a 100 percent amount(the full VSL). We therefore value asymptomatic cases at about $11,000 (in 2019 dollars) each which corresponds to using a 0.1 percent amount of the VSL in DOT (2016)."
0.1% of a statistical life is about a month? It's also a third of the "minor" classification.
How would you value it? $0? Clearly, that's not right.[1] Less than $11,000? More?
[1] Consider a new infectious disease which has only minor symptoms immediately, but may have unknown health consequences in the future.