We don't "know" it, but that is the usual experience. Why should someone put more effort and cost in making a fake? Typical fakes - and lets not even get starte

We don't "know" it, but that is the usual experience. Why should someone put more effort and cost in making a fake? Typical fakes - and lets not even get started on replacement parts for cars or even airplanes - are not only carbon copies to save the design effort, they are not using the same production processes. And these are very important insuring the quality of the product. Fakes might use cheaper alloys, the production process itself might not be as required and quality control missing. And so a fake bolt can have only the fraction of the load capacity of the original one. Edit: And of course, the beauty with a fake is, that if it fails, the blame does not fall onto the producer of the fake, but even possibly of the original brand ribbed of... another incentive not to make overly well built fakes.