technology/electrical/Have you ever wondered why in some places it is 50Hz? or 60Hz

Have you ever wondered why in some places it is 50Hz or 60Hz?as a student i wondered why  in  some  place it is 50Hz and others 60Hz power generation ,i had  a thought over it .I was searching for Pros and cons of countries use 50Hz or 60Hz,and after few internet searches ,i found out that there is no advantage or disadvantage of using 50Hz or 60Hz ,then  i wondered why countries use different different frequencies of power generation.The solution to this mystery is that The German company AEG (descended from a company founded by Edison in Germany) built the first German generating facility to run at 50 Hz. At the time, AEG had a virtual monopoly and their standard spread to the rest of Europe. After observing flicker of lamps operated by the 40 Hz power transmitted by theLauffen-Frankfurt link in 1891, AEG raised their standard frequency to 50 Hz in 1891.

Westinghouse Electric decided to standardize on a lower frequency to permit operation of both electric lighting and induction motors on the same generating system. Although 50 Hz was suitable for both, in 1890 Westinghouse considered that existing arc-lighting equipment operated slightly better on 60 Hz, and so that frequency was chosen.The operation of Tesla's induction motor required a lower frequency than the 133 Hz common for lighting systems in 1890. In 1893 General Electric Corporation, which was affiliated with AEG in Germany, built a generating project at Mill Creek, California using 50 Hz, but changed to 60 Hz a year later to maintain market share with the Westinghouse standard.

so,the gist of this is that due to maintain market share ,companies used different frequencies of power generation.