Pat Myron's Quick takes

Does PPE not work or is the issue that people don't use it?

Nice job bringing up an interesting idea. Having not read any of the research, here are some naïve ideas and musings:

• It would be interesting to a see a quick-and-dirty cost-benefit analysis: what would it cost to replace 99% of "traditional" lawnmowers with autonomous mowing robots? How much money (or QALYs) would be gained/saved? What price would a robot mower have to be for a person with a one acre lot to justify buying it. Or maybe alternative models exist, in which I rent the robotic mower for two hours rather than purchasing it.
• We could make a clear argument that people simply shouldn't spend money/time/effort moving their lawns, as the risks/costs aren't worth it. But many people (in the USA at least) would continue to do so because they place social value on the appearance of a well-kept home.
• If there are about 82 million homes in the USA (this is from quick Google search, so I trust the number about as much as I ought to for having not looked at the sources), that implies 85,000/82,000,000 that about 0.1% of homeowners go to the ER each year for mowing injuries. This is of course completely ignoring non-home mowing, such as sports fields, corporate/office landscape, etc. This is also ignoring all the people that get injured but don't end up in an ER visit.
• Safety features have presumably improved in movers during the past few decades. I wonder what the distribution is of the injuries in relation to how safe/new the mower is. Maybe a majority of the injuries are caused by half-broken mowers, or mowers from the 1980s, or from mowers that don't have an dead man's switch.
• I wonder if there are other, more important causal factors. Maybe most of those 85,000 involved people mowing the lawn while drunk, or elderly men insisting they they are still "man enough" to take care of the yard, or teenagers goofing around. To the extent that is accurate, the narrative might change from 'mowers are dangerous and should be replaced' to 'drunk people operating machinery are dangerous.' The parallels to cars are petty obvious: cars don't cause accidents, people cause accidents. But that doesn't deny the fact that a robotic car can avoid many of the accidents.
• I'm guessing (again, I want to emphasize that this is a naïve guess rather than a well-informed guess) that a majority of the injuries occur in situations that a robotic mower wouldn't be very suitable for. I'm mainly thinking of small lots and areas with steep angles, such as the picture below. There are strong parallels to Roomba-style vacuums: they are great for houses with particular layouts, but many homes exist that are simply not practical/feasible for that type of robot vacuum.

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I disagree because I think writing text to indicate a sentiment is a stronger signal than pressing a button. So while it’s somewhat redundant, it adds new information IMO. 
 

As a writer, I pay attention to these signals when processing feedback.