Oregon was the first to pass the legislation n 1971 and it became active in 1972. Below is a a copy and past on the number one reason.
"The law is credited with reducing litter and increasing container recycling. As a result, items which used to make up around 40% of roadside litter now represent about 6%. With return rates averaging 90%,[2] another major benefit is in waste reduction and resource conservation, particularly for aluminum. By comparison, states without similar bills recycle on average 33% of their containers.[3] Beverage distributors retain all deposits not reclaimed by consumers."
You pretty much never see bottles or cans roadside in Oregon. If/when you do it rarely sticks around for more than a day due to lots of folks taking advantage and picking them up. I am am out in the country 7 miles from the nearest stores. I regularly see folks walking the roadside ditches with bags filled with empties. Our Boy Scouts volunteer to pick them up from your house if you don't want to be burdened with returning them. This is a solid fundraiser throughout the year and even better when events are held like our local Oktoberfest. I recently bumped into an older gentleman at the store that I often see walking the roadside ditches. I asked him how much he makes doing it. While he would not share actual numbers he did elude to what I figured to be around $40K per year. He is retired, out getting his exercise, and helping to put multiple grand kids through college. Not to mention helping to keep the roadside trash at bay.
The Oregon return laws were just recently amended to include lots of other recyclables. Just yesterday the wife noticed that her large plastic bottle of V-8 juice now have 10 cents on them. While it might seem like a real joke to most to go to Costco and buy bottled water for $.08 and have to pay $.10 deposit on each bottle, it will and does keep these items picked up and recycled. I am all for keeping more plastic out of the dumps. Our bottle bill now includes almost any and every drink bottle including aluminum, plastic, glass, and even the steel imported juice cans. Those states that don't agree with the time, hassle, and expense of enacting similar systems to the "Oregon" laws, certainly will go on seeing plenty of it roadside and in your dumps. Having grown up making a difference and benefiting personally from the extra dollars earned, I have a tough time understanding why the "Oregon" laws on bottle returns have not been enacted nation wide. After 45 years we know it works. It is about time other states take notice and make it work everywhere.