My gut is that the government wants services that work for 100% of people. In terms of purely costs, people who can't use a site may need to be serviced anyway by more expensive means (e.g., voter registration by mail).
A business probably thinks that it doesn't need 100% accessibility. A nicer site may be thought to get more users/customers, even if the site doesn't work for many (or maybe devs just want to fit in with the other cool devs making cool dev sites)
A business probably thinks that it doesn't need 100% accessibility. A nicer site may be thought to get more users/customers, even if the site doesn't work for many (or maybe devs just want to fit in with the other cool devs making cool dev sites)