The tl;dr is because we do not have one world government.
The universal data format for resume has attempted - both by public and private sector actors. The Europass CV is a good example of the former, a universal profile for all EU citizens, which can used to apply for any job posted on the platform. LinkedIn might be considered a private sector attempt of the same.
The issue that confronts both is adoption rate.
Without forcing it through via mandate, employers will continue to accept resumes in whichever format and so job seekers will continue to optimise for the format they think will give them the best chance with said employer.
Diversification comes from the simple fact that there is no single authority enforcing standardisation
The universal data format for resume has attempted - both by public and private sector actors. The Europass CV is a good example of the former, a universal profile for all EU citizens, which can used to apply for any job posted on the platform. LinkedIn might be considered a private sector attempt of the same.
The issue that confronts both is adoption rate.
Without forcing it through via mandate, employers will continue to accept resumes in whichever format and so job seekers will continue to optimise for the format they think will give them the best chance with said employer.
Diversification comes from the simple fact that there is no single authority enforcing standardisation