There's a world of difference between individual policies - or just ideas - that are popular in a vacuum, and an actual prospectus for government tied to a party and a candidate. These questions are all going to give pretty feel-good results:
- Do you like free-at-the-point-of-use healthcare Y/N?
- Do you like the abolition of tuition fees Y/N?
- Do you like digital giants paying their fair share of tax Y/N?
- Do you like the idea of a higher minimum wage Y/N?
But I bet the picture becomes much less rosy if you ask:
- Do you like this list of policies put forward by a Democrat administration, led by X candidate, at approximately Y cost?
You literally couldn't ask for a better example of how 'popular' policies are no guarantee of success than the recent UK GE. Labour's offering included the nationalisation of broadband and the railways, the introduction of higher rates of income tax and greater wealth taxation - all policies with 50%+ approval - but offered as part of a package with Jeremy Corbyn at the helm, voters proceeded to give the Tories their greatest victory in decades (almost half of respondents also said that, taken collectively, the manifesto was too extreme):
https://twitter.com/ChristabelCoops/status/1219207011138789376