All around Taipei food vendors will set up little stands and stalls to sell their food. As with most traditional practices that still continue here, the legality of it is very grey. It's illegal to set up your stand on the street, and if the cops come by, the vendors will quickly push their stands away (well as quickly as possible) however there seem to be some areas where it's ok to be on the street. I believe in these areas each vendor must pay a fee to have a small part of the street just for them to put their stand up.
What many vendors do is go to some shop and ask if they can set up their stand in front of the shop. Of course they have to pay the store some money for using their "land" but the benefit of this is that they can legally be there and not need to run away when the cops come. But since there is no binding contract in this relationship, sometimes the vendors are quickly kicked out and replaced by one that is willing to pay more. One vendor I really liked, ended up moving their location three times in one year cause the "rental" prices both in front of stores and on the street, kept going up.
To get around having to "rent" some land, some people have motorized or peddle carts. they will constantly go around the neighborhood waiting for somebody to flag them down and buy something. I guess it's a good idea, but I kind of dislike these kinds of vendors. This is because they also are accompanied by a constant sound clip advertising their food, projected through a megaphone or loud speaker. You're not taking a nap when several vendors are going around in circles outside your house blaring their food's quality.
Why go through all this trouble? Well these small vendors can make quite a lot of money. I know a few people that have them, and even a mildly successful one can clear 2,000 USD profit a week. It's hard work, in a cramped space, and the weather can be cool, rainy and windy; or extremely hot and muggy out. But if you do it and do it well, you can make more than restaurants do. In fact those that go from having a stall to opening a restaurant usually end up making a lot less money. But I guess for them the comfort of having a nice indoor place all your own, is worth the lose in revenue.
There is a flip side however. Having a stand can be so prosperous that some vendors will buy a very old dilapidated building for next to nothing since nobody can even get in the building, just so they can put their stand legally in front of the building they own. They will just leave the building falling apart, looking half destroyed from an earthquake or typhoon or both, while they rake in the money from their little stand.
In the picture is one of the notorious sound culprits in my old neighborhood. To my former roommate and I he is famous. This is because whatever his sound loop was saying in Chinese, it sounded to us like it said "Hooray...pork chops!" in English. It was extremely loud and sometimes annoying but occasionally it would make us laugh. To this day I have no idea what he sells (even though I did stop to take this picture) and no clue what he is actually saying in Chinese.
There was one other vendor who would make us laugh. Again we never knew what he was actually saying in Chinese, but in English it sounded like he was saying..."F***********ck Spike Lee!"
