My brother in law leaves overseas and he digs a big hole in the back yard and throws all the dog waste in there, when full he closes it with dirt.
His reason is it attracts worms.
Did anybody try this? Does it work? Does it attract the worms on it's own or do we have to add some to get it started?
I dug one hole this week and started doing it to reduce waste. Dog waste was one of the few things I put on the trash. Mostly everything else is recycled or composted. But I don't want to do that if it is just an old wife's tale...

Like any animal manure dog stool is a form of organic matter that the earthworms will work on digesting. Because of that some people see no reason to not compost dog stool not realizing that since dogs live so close to us that they can harbor diseases that we can catch, as well as intestinal worms.
If you have enough space to bury the dog stool for as long as you have that dog that is as good a diposal method as any, sending that out in your trash essentially does the same thing, just further away from you.

I do have space to bury it far from the garden, but I want to know if it will really make a difference in the worm population and quality of the soil, or I'll just be breaking my back diggin holes in a very hard, compacted soil, ravished by pine trees...

Don't bother. As Kimm1 stated, dog (& cat) stool carry pathogens that are easily transmitted to humans. Worms or not - it's best to dispose of these wastes away from human contact. Depositing them in holes in your yard is NOT going to make any difference in the quality of your soil. Old wives' tale.