“Cost is not a good argument [to not do it]” is the actual line taken with the ADA for public accommodations (which includes most private businesses). There is a reasonable accommodation rule as to how an accessibility function may be implemented, but not if, and the rule scales with the resources of the provider.

The result of which is, in the USA, a person in a wheelchair can enter nearly every business, use many public restrooms, and generally participate in life on their own.