What was considered a luxury 100 years ago, but is common today?
Just naming a few things:
dental care

Image from the documentary about the First World War called ” They will never grow old “.
passenger cars
Amsterdam in 1920.
Amsterdam, 50 years later, around 1970.
Back to bikes and streetcars, another 50 years later.
cameras
Mary Pickford with a movie camera in 1916.
100 years later; bystanders recording incidents with their phones.