That's a great question; I suspect that there are quite a few pretty big $ software firms doing vertical market software enterprise apps for specific types of enterprises/entities with unusual requirements who are happy that few know how successful they may be. Are there dominant software providers for any of the following (bigger than mom-and-pop businesses, with many organizations in the industry):
1. Large construction projects
2. Paper mills
3. Motion picture production
4. Oil and gas drilling
5. Cattle ranches
6. Local property tax assessment and collection
7. Traffic ticket and traffic court management
8. Water works and/or Sewer plant management
9. Prison management
10. Automobile junkyards
11. Parking lots and parking structures
12. Independent bookstores
13. Rental property management
14. Exercise clubs
15. School districts
16. Churches
???
Somebody spill the beans, please.