I also admit that before doing a simple research online I used to believe on this myth. I think the reasons which made me believe it is true back then might be a bit similar to most of those who still believe this is true.
I believe there are many other reasons which make people believe on this myth that friction is the source of friction.
There are number of studies or experiments done by proffesionals can help to completely remove this myth. For instance our houses are grounded to prevent bad effects of lighting during rain seasons.
Benjamin Franklin introduced lighting rod in 1750, his experiment involved flowing a kite beneath a thunderstorm which resulted in electric charges being transfered from the Lightning. This experiment resulted in the common wire normall put on houses which goes to the ground. This wire act as a protective item to humans because if the Lightning strike it all of the charges which causes static electricity will be directed to the ground and not to the house. This experiment proves that the adhesive force is the one that causes static electricity and not friction.
Newtons Coulomb's law of electricity shows that the electric force is proportional to the product of charges. And two opposite charges attracts each other due to the adhesive force generated when two bodies of different charges are brought close together. Therefore, This conclude my article by a proof from expert that it is not friction that causes the static electricity but it is the force due to opposite charges which causes negative charges to be transfered to the more positive object.
Thank you for reading and please feel free to contact me if there is any information which is not clear or if there is something wrong.