The licensing terms are identical to similar projects including OpenFoodFacts (which also has an app) and OpenStreetMap, see:
https://wiki.openfoodfacts.org/ODBL_License
You may disagree with each of those projects as well, but, I am following long-standing licensing in this space. I also have used some OFF data for product naming, and as a result, their terms state I have to maintain their license.
Creating these databases involves a tremendous amount of time and effort, and it would not make sense for me to make this data available to commercial entities to use without attribution. The alternative is not a MIT-licensed dataset, it is no dataset.
The two you cite, OpenFoodFacts and OpenStreetMap are non-profit/not-for-profit, known for their databases, not for competing commercial apps.
I appreciate the difficulty of building a good database. Can you say why you created a new one, rather than starting with OpenFoodFacts? (Was it quality issues? Too hard to update? You wanted additional info? You didn't want their licensing terms? You wanted the advertising boost?)
I've explained why OFF is not an adequate source in and of itself for a food logging app elsewhere in the thread. If it were usable in and of itself, I wouldn't have had anything to build on the database front and would have just used it as-is.
https://news.ycombinator.com/item?id=43570775
Thanks, that part makes sense.