Even Hospitals Today For The Most Part
Have moved to throw away "wash cloths", as opposed to my day when they were pure cotton terry. Why? All those wash cloths and such heavy with feces and such now require separate laundry bag labeling,and different proceedures than other laundry. One nurse told me that the laundry her hospital uses actually sends anything heavy with feces back, though find that hard to credit.
A person we know out here started a diaper service, but along European lines, using detergents and activated (TAED)oxygen bleach EU certified to sanitise if wash temps are at least 140F for twenty minutes, or 160F for ten, IIRC.
They were using stean heated washing machines, so don't know about their costs.
Mothers, hospitals and doctor's offices are very particular about their laundry. One mother's infat comes down with a bad reaction to the diapers, and you are on "Yelp.com" or the "Mommy Message Boards", and there goes your reputation.
Also consider with a diaper service, there is little to no room for missed deliveries/collections. Infants go through vast amounts of diapers per day, and a mother that has to either wash her own or do without because of a missed day (weather or employee related), is not likely to be happy.
Mother's in particular can tell how "clean" a diaper is by how it smells wet. Again, if they sense something isn't right, be prepared for some telephone calls.
Consider also one has to order vast amounts of diapers surplus to requirements for two other reasons:
Customers use diapers for all manner and sort of things besides baby, ranging from rags to cleaning up cloths.
Next the harsh laundering requirments (high wash temperatures and or routine use of chlorine bleach) will shorten textile life. Once a diaper starts to show wear such as holes or other damage, quality services will retire it from service. Some diaper services sell such diapers as "rags" to recoup part of their investment.
Also today a diaper service rarely has only diapers, but offers several types of covers, wraps, and so forth. Again all of which requires an outlay of investment.