1. Machines and software tend to be fully amortised.
2. In theory, Maintenance contracts would be costly and spares difficult to find. In general this is not perceived by the users as an issue. They can usually pick up cheap replacements in the Wanted/For Sale ads or from some tame CompuGeek or sleazy backstreet outfit...
3. In the business scenarios the benefits accrue from keeping overheads low, and minimising Capital expenditures.
4. In general, there tends to be sufficient, even excess capacity. So the business can still grow in volume.