... do they get a written reference at the end of each job?
This is unfamiliar territory for us. My son has been trying to get his first casual CSCS Labourer role. Most of the advertised jobs ask for references in a way that implies they expect you to be able to send them pre-written along with your passport & Green Card, rather than just supplying a name of a referee for them to contact. Is that the norm in this line of work? Not sure if we're misinterpreting.
He doesn't have references for any previous labouring roles but, if he manages to get a job, he's wondering if he needs to ask for a written reference at the end.