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To address a couple of the things you mentioned:
Better education: It's true -- when it comes to health and nutrition, there's a lot of misinformation out there and a general lack of knowledge of even the basics. Most people are not great at determining how many calories are in a meal, whether something is good for them, or even just remembering what they've eaten on a given day. There's a huge opportunity for technology to help people figure this stuff out and learn to make better choices (full disclosure: I work on an app in this space [1]).
Taxing unhealthy food: While we can't levy taxes, there are ways to provide similar incentives, for example by automatically giving people cash rebates when they purchase healthy food [2].
Can the tech industry solve obesity on its own? Maybe not. But I'd argue that trying to address what we can is a better option than throwing up our hands and saying it's a social problem.