It's bad in a lot of Western countries, but in many developing countries it's truly horrifying.
In Morocco, a country of stunning natural beauty, people truly tend to drop whatever they no longer need exqctly where they are standing and then walk away. This includes police officers, so I can only surmise that there simply is no littering law (although their recent move to allow only (semi?) disposable plastic bags seems to make a clear difference for the amount of airborne travellibg plastic). In addition to that, even the most beautiful quaint little oasis towns have their open air gqrbage dumps, such as in this photo, which smell truly foul.
Above: large scale garbage dump at the middle of nowhere city of Dakhla. I think it is collected by the municipality, and then dropped just outside of town and burned. It's also about 100m away from the Atlantic, so plenty will still make its way into the sea...