It's certainly not normal but it's frankly inevitable. All it takes is some fraying wire, failing insulation, manufacturing defect on the PCB or components and something slightly flammable nearby (usually the product itself). That and how much stuff people usually have plugged in, somebody is going to experience a fire eventually.

Regulations on Chinese garbage are practically non existent. There are countless cheap chargers that will start fires. One nearly caused one in my home as a kid.