Sasha
Even beyond the EU Commission, the national governments of Europe are primarily composed of parliaments. Under a parliamentary system, there are far more frequently conditions of "unified government" that allow for the passage of more widely ranging legislation at a faster cadence. The American federal republic was constructed specifically with the dangers presented by a parliament in mind. During the Revolution, Boston clergyman Mather Byles was remembered for saying "Which is better - to be ruled by one tyrant three thousand miles away or by three thousand tyrants one mile away?" While European legislators have the advantage in passing laws more quickly and easily, it also becomes possible for populist leaders to wield more authority. For example- the current situation in Hungary.
In the US, it is possible for a smaller number of elected officials to become obstructionistic, for one side of Congress to block the other, or for the President to veto a unified Congress. When I mentioned the "fight right now" about the military funding travel for abortion, it was really only a single senator (and retired football coach) from Alabama who has been gumming up the works. That's why generally, Europe is about 30-50 years ahead of the US when it comes to advancing initiatives like abolishing slavery, civil rights, socialized healthcare, consumer protections, privacy rights, etc. The tradeoff is that by making it harder to pass laws, it also makes it harder for the government to institute new ways to oppress its people when an authoritarian does come to power.
The problem with having a less robust legal doctrine covering all possible judicial scenarios or the ability to quickly pass new laws to address them as they arise, is as you point out, that it gives the judiary wide latitude to implement its own precedents. And because of the geographic distribution of prevailing political affiliations across the federal courts, and the selection of activist judges by presidential nomination and senate confirmation, the courts themselves often become proxy battles by issuing conflicting rulings.
The legal justification for those rulings sometimes verges on the comical. Ancient laws get revived because they are literally the latest law that has anything to say on the matter. The current case to outlaw the distribution of abortion-inducing medication goes back to an 1873 law that prevents distributing "obscene materials" through the US Postal Service. The case that backed the executive resolution that was used to prevent entry from a variety of Muslim-majority countries by a recent US president went back to the Chinese Exclusion Act of 1882, a decidedly racist law that was passed by nativists on the basis of there "being too many Chinese here." When the FCC voted to regulate the internet as a public utility during the Net Neutrality fight in 2015 in which Netflix was accused of receiving priority broadband access, it did so on the basis of a law from 1934 which governed telephone switchboard operators. I could go on and on, but you get the idea.
