Wondering if he means the thresholds are off. I imagine erring on the side of caution is the smarter thing to do re: liability. Imagine if a cyclist couldn't hear a quieter electric car and turned into its path because the headphones are geared towards a low band pass.
I see — have you tried Jabra? Their in-ear headphones have a great pass-through mode (as well as ANC/others) that work really well for me when I'm running.
I was expecting that the surrounding sounds blend in with the music instead of drowning it out. Like you can hear music coming out of a speaker while a car passes.