1) that the lead is not entering the food chain upstream of the grocery store where one buys one's apples, sweet potatoes, rice, greens, or whatever one is purée-ing into one's own baby food. There's no reason to believe that the lead is a result of the factory process. Since industrial food processing machinery has been lead-free for far longer than the current equipment lifespan, there's little chance that the lead is coming from those stainless steel machines. Which means it's in the food chain. Therefore, unless one is in control of the whole watershed that waters one's garden plot and pasture, has 200 years of records on that land's uses, kept that land inside a glass bubble during the majority of the 20th century, controls the wind and precipitation on that land, and eats only from that improbable garden plot, there's a good chance the lead is coming from the food, not the packaging. Most of the environmental lead is due to lead particles from 20th century leaded gasoline settling into the soil, lead paint flaking off of buildings and fixtures and washing into the watershed, and industrial lead leaching out into watersheds and soil. If the lead is in the food chain, DIY baby food is also likely to contain lead, possibly at higher concentrations, since most households don't have the means to test every batch of food.
2) assumes that everyone has the time, skill and tools to make their own, and assumes that child carers are willing and able to accept whatever home-brew purée gets packed in the baby's bag. Just like day cares usually don't have the facilities to deal with cloth diapers and thus insist on disposables, they may insist on sealed, commercially jarred foods because there's far less of a chance of the far more common food-born illnesses in sealed jars, and less chance of the major allergens that can affect another child. Maybe the DIY hipster Wellness Mama Woo model works for highly privileged, affluent, stay at home parents with no commitments on their time, but most working parents at least occasionally need to use commercial foods, because most working parents don't have infinite time, skills, tools and resources, and because parents and infants may have to travel beyond their perfect little HGTV bubble. If you're evacuating with your baby due to flood, fire or earthquake, the frozen cubes of squash aren't going to be available at the Red Cross shelter after a day or so.
3) We should in fact be able to trust our food system. Would you prefer the tests never be done and/or the results not be published, or that we do the testing, find the source, and fix it? We can't fix it if we don't know it's happening. We can't know it's happening if we don't test.
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