[Ham-Mac] station co-ordinates

[Slater Tubman]

I don't know if this is the proper forum to ask this, but here goes:

I use MacLoggerDX4.2.2 and it is a lovely program.  When I enter a  
call and ask it to look up the operator's name and QTH it also  
returns the latitude and longitude readings.  I always assumed they  
are correct however when I entered my own co-ordinates and those of  
nearby hams (withing 40 miles) the resulting given co-ordinates are  
away off...by anywhere from twenty to one hundred miles.

What is the source of co-ordinate data that the free internet lookup  
accesses in searching?  I don't have the QRZ CD, but even it was  
incorrect on the website as far as my own location is concerned.

If government license data base is used by the program, how in the  
world can we access it to determine accuracy?

73
Slater Tubman VE5OA