Why can’t lawyers do what doctors do for the poor, that is, offer their services at free or low cost.
Actually lawyers do just that in many jurisdictions. Fees for court-appointed cases are typically much lower than market rate. And I know of at least one jurisdiction (Jackson County, MO) that assigns idigent clients to resident attorneys for no fees. I don't know how much good this really does the clients, since it's not unusual for, say, a tax lawyer, to get a termination of parental rights case assigned to him. It's kind of like asking a psychiatrist to do surgery.