Short term customers get fleeced once.
Long term customers are kept by offering pratical solutions, its up to the installer to make his profit out of screwing suppliers, look how many of them drive flash cars!
Personally I look at the customer and decide what they are willing/able to spend and quote accordingly, a charity is hardly likely to have the cash for a full upgrade but up in the big city they like to spend their cash on systems to make the tenants more likely to stay, it only takes half a dozen false alarms in the winter with several hundred employees outside for the tenant to start looking elsewhere.
Back to the original topic
, you can but advise them and quote to the standards, I am pretty sure care homes have to fill out H&S reports for their license on an annual basis, if they choose to ignore the fact their system is non compliant and predates 6 years of standards requirements they are not going to win any court battles, it may take a bit of effort to make them see sense but they will appreciate you in the long term.