There are many different types of laundromats including industrial, apartment building or college dormitory-style, mom-and-pop family business style, and supermarket-style which offer coin-operated machines that offer detergent only. For example, if someone works the night shift or is on vacation and needs to wash clothing in the morning, it would be inconvenient for them to go all the way home first before going to a laundromat.
Laundromats are also good for people who need to do their laundry at odd hours. Laundromats are a convenient and quick way to clean clothes, especially during emergencies.