You scrub my back i scrub yours, we get 1 dollar each.

Was walking down my neighborhood one night, just admiring the quiet environment when suddenly i notice those push cart you push around while your in the supermarket. You put 1 dollar in and you get a push cart. But if you push it back home you will have trouble trying to get the 1 dollar out, but i'm sure with some hammer and screw driver it won't be a problem just time consuming and loud noise will follow.
But someone found a faster and effective way to overcome this. By using another 1 dollar and a push cart.

This is something you won't expect while walking around but further inspection shows some interesting intertwine shape

This is some very interesting idea. If they use it to solve global warming.

Conclusion: From what ever idea that they have when this was done, 1 thing is certain. They are willing to spend another 1 dollar and waste another cart to get back 1 dollar only. that's SGD300 on the street. But they took back their 1 dollar only. Not a very smart move but i guess they don't want to get into trouble with the police.