From a quick search (not some verified peer reviewed source deep dive), transportation seems to be about 30% and food 17% of USA household emissions. Calling it 1% is marginalizing the impact people can have with a very simple change.

Also note that buying a different product in the supermarket is an entirely different order of magnitude than changing your life around so that you can cycle to work without less free time / degrading quality of life. I'd argue there's sense to recommending doing low hanging fruit.