I don’t know where you’re hearing retailers don’t enforce ratings. Yes, it happens uncommonly, but the FTC previously found ratings compliance was higher among video game retailers than at the box office, and not much has changed in the culture since then. I’ve worked at multiple retailers that sold video games, and the training for video games enforcement was always taken just as seriously as with alcohol sales.
Being the largest entertainment industry in the world now, video game publishers are serious about this stuff. Developers also still take steps to avoid a Hot Coffee situation from occurring again.
Similar visual design happens all the time in Japanese media and there’s rarely litigation over it. Patent lawsuits are much more common in Japan.