I have searched for recent graves of ancestors, but no one past my great-grandparents though. I have found that most of them who died as recently as the 80s, if that can be considered recent (haha), do not have grave markers.
I used to be puzzled over why so many of my relatives didn't have them. Why? Well, they are too damn expensive! I priced some locally and the cost is astronomical for these markers! I believe they were unaffordable for my ancestors too. So years go by after the person dies, people return to their regular routine of life, and family members sometimes move to different areas of the city, state or country - all is forgotten.
Then you have a family historian, like me, come along. Where's the grave? I checked the death certificate, it shows where they're buried, if the cemetery still exist you call the office, and they inform you, "this person is in an unmarked grave." Here''s another scenario, you join findagrave.com. You can request others in the area where your loved one is buried to go and photograph the grave site. Usually the results are good but a few times they write back that there is no marker. I can't be embarrassed nor ashamed because I already know that the family couldn't afford a marker. I learned with colored (graves) cemeteries there were many restrictions on the type of marker that could used. I could imagine someone going home and making a wooden frame, pouring some concrete and making the imprints before it completely dries.
These unmarked graves in my head makes me want to do something and not just write about it. It sort of haunts me. But, I want to make sure each grave has an identifying grave marker. I feel as though the ancestors want me to honor them by procuring the funds necessary to ensure that they are recognized in death.