Civil time is a coordination game, so "leave time alone and just get up later" is more complicated than you think.
Imagine how it would look if everyone kept acting the same way we do now but the clocks don't change. Everyone would need to post summer hours!
Here's the Sun Graph for New York City: https://timeanddate.com/sun/usa/new-york
Notice how the DST transition keeps sunrise relatively constant? That's actually a decent feature, particularly for people like me (and people with young children) who tend to get up with the sun.
And they'd need to tell you when those hours start and end. In practice it would be a random mishmash of DST transitions on a per-service basis.