These pictures are from a recent weekend at the Meads trailhead on Overlook Mountain. The popularity of the hike means that the trailhead parking area is full to capacity early on any weekend and on many other days, too. People then park on the sides of the road, often illegally, which creates hazardous conditions for drivers and pedestrians. The narrow road can become difficult for 
emergency vehicles to use, so it is crucial that hikers park legally. You can download a map of the area below, which will help you avoid getting a parking ticket. 
Print PDF map here: Overlook_parking
It doesn’t help that people from the nearby “conference center” use the trailhead parking area as an overflow. I have seen this several times when I was there. I agree with you that hikers must park legally to allow access for emergency vehicles and to respect private property. One option is to park at Platte Clove and hike in from that trailhead.