dotcode
… except that you appear to adjudge a negative financial value to accessibility compliance, when in fact the opposite is true.
Yes there is: the Americans with Disabilities Act. Many private businesses in the States have been - and are currently being - litigated against under said act.
The mandate of the ADA is to provide "full and equal enjoyment" of a public accommodation’s goods, services, facilities, and privileges. Places of public accommodation include, "place[s] of exhibition and entertainment", "places[s] of recreation", and "service establishments". The vast majority of websites are therefore "place[s] of public accommodation", are bound by the requirements of Section 508, and - since roughly this time last year - are required to meet WCAG 2.0 AA (https://www.access-board.gov/guidelines-and-standards/commun...).
In the States businesses are also required to meet the requirements of various human and civil rights laws enacted by states and cities.
And if your company has an international presence, it's also covered under whatever legislation exists in those jurisdictions.
Basically: hell yeah there are requirements to make web content accessible to disabled people. Almost whatever you do, wherever you do it, will be covered to some degree by legislation designed to prevent discrimination.
Of course the existence of financial/technical incentives are good reasons for businesses to make sites accessible, regardless of any legal requirements.
In terms of benefits of using Shunter over a home-rolled solution, the same question could/should be asked of any framework. Shunter is very well tested, has been used in production on a large site for a number of years, and is used to serve hundreds of thousands of requests. It will also be supported by a large development team for the foreseeable future.