I think you're reading way too much into the rhetorical touches in the article. There's an interesting contradiction that one of the busiest shopping areas in the nation also being the only place left with a wide-ranging Sunday shopping ban. That's really what this article is about.

It's not about the fact that municipalities can have different laws, which is not unique to the United States, and I'm curious if you have evidence that "the modern left dislikes" the fact that cities and states can have varying laws. I don't have that impression, but it does make for a convenient straw man.

The left and the right both support state and local experimentation when it suits their desired outcome and they both support national power when it suits their desired outcome. The political parties may pay lip service to political philosophy, but in practice they take advantage of whatever philosophical argument works best for the outcome they wish to achieve. See: slavery, fugitive slave laws, segregation, voting rights, same sex marriage, marijuana legalization, abortion, labor organization, union busting, immigration, environmental protection, consumer protection, universal health care...