Not only there are multiple brands for the same thing, but they make sure that the accessories only fit their own brand. For example, you can't use batteries from one brand on another, just to force the consumer to buy the same brand, or buy things they don't need.
That's right, it means people have to stay with the brand and if they do not want to the cost of swapping over is huge...and then one has to stay with that brand because of the cost of changing...again.