Are doctors really not motivated enough to treat seriously ill patients older than 70 years old?

Some physicians are reluctant to treat older adults dealing with suicidal thoughts and tendencies than younger people with the same problems. My grandpa was fighting depression in his last years because of my grandma’s passing away, and we tried so many therapists and physicians to find someone who does something.
Some physicians assume that being depressed and having suicidal thoughts when you’re older is normal and logical. Hence, they are reluctant to use some strategies in older people’s treatment.