It's the US Government, why would you want to have a car sound like something that people walking can immediately identify as a car instead of "WTF is that?" The law just has frequency bands and loudness requirements.
Here's one from the Chevy Silverado EV, similar to my GMC.
I think they reduced the volume a bit in the later software or I'm just mentally ignoring it now.
Also, it still makes noise when stopped unless you put it in park, so at a drive-thru you get to put it in park to not horribly annoy the person taking your order.