I have owned ( at 17 my total was about 80 of them ) many tac- force, wartech, duck brand, mtech, frost cutlery, bullet brand, tiger usa sharper brand , and generic folders that came in a silver box simply marked " super knife "that I used to buy from the flea market or my dad would buy me from cutlery corner.
There were a couple that I carried and used, but the rest I kept in their boxes. Some I passed on to my cousin who keeps them in the boxes as I did, most of the rest I sold in a yardsale to a guy who just wanted to collect them.
My brother still keeps buying them as users even though they always fall apart on him.
According to him " I don't want to mess up a good knife " and apparently a 20$ buck bantam is even too good for him to buy and use. They wouldn't keep falling apart if he would loctite every fastener on them, but it costs more than the 8$ the knives cost.
I would not call them inherently unsafe Because generally proper use negates the need for any kind if lock, the liner locks on many if them probably should be trusted and relied on less than something better but mine were never that unsafe.
most of them held an edge OK for light duty EDC , but these reasons aren't why I wouldn't buy them.
I won't buy them because most are assisted opener's which I don't like, they miss the mark as far as practical design is concerned by using certain design elements " just because " without knowing the purpose for them, and in general they are the epitome of what I dislike about the design of 90% of modern folders today.
95% of these cheapo's aren't worth the 5-10$ they cost, but every once in a while you find something like the Ozark trail knives that are worth having as a beater knife.
I've got a 5$ knife I've had for about 5 years that I actually still like and use some times that ill probably post a picture of.