Yeah, my mom tells me stories... and her case it was poverty that gave her short skirts so being scolded by the nuns just made it worse.
Where I worked there was a "uniform trade-in" operated to keep money issues from making the skirts too short. As kids outgrew uniforms, they could be traded for used ones in a larger size. Nearly every family used that regardless of money, because it was convenient and cost-effective. You left an item and took an item--no money involved.