Agree completely. I grew up in a residential area similar to JJ's. If something like this happened in the neighborhood where I lived & if people were home, it's possible someone would have glanced out of their window to see what happened. That is - if they heard anything.
However, note that if it happened this way the whole thing would probably have occurred very quickly - I can see everything happening in maybe 2-3 minutes, from beginning to end. And, even if someone did hear something, they may have been in the middle of doing something and/or in their back-yard(s), etc. So, by the time they came to the front of the house to look at the street - the car/JJ may have been gone.
Also, note that JJ's disappearance was in 2001. Yes, there were undoubtedly people at home during the day ATT (retired people, kids if school had let out for the summer, spouses who didn't work, etc.). However, this happened long before remote work became as popular/wide-spread as it is now. So, I suspect many (and maybe even most) of the people that lived in these houses were at work during the day.
Lastly, how do we know that someone out there didn't see/hear something & just didn't report this?! We have no way of knowing this.