I dunno GG one minute you're out to get people that pay for things to get ahead, the next you're supporting it.
All of the employers Ive worked for have supplied the DG certificate and renewals.
Once you're employed, then yes, the company should cover it to keep you current. It would be like saying 'why should I pay for a MECIR or NVFR rating? If the company requires me to use it, they should pay for me to get one'
In terms of endorsements and the rest, then yes, the company should pay once you are an employee.