Any work over a certain limit done for any government body, nhs, local authority etc. Goes out for tender and it's the client that tends to via a consultant, designer that would specify what is to be used or what's not to be used. The client is more or less looking for the cheapest cost to get the job done. Which in turn forces the contractors to under cut one & other and cost save where they can i.e. cheap labour/cheap inferior materials. The bullet stop with the client as they have overall control of any project.