Site managers are concerned with operatives having the relevant H&S qualification.
A valid and in date CSCS or ECS card is proof of this.
Photocopying the card is just record keeping.
The various trade Managers are concerned with the operatives having the qualifications required to do the work.
The colour of of the trade card should be proof of this.
I’ve worked on sites, where not only do they require operatives to produce physical forms of ID and Trade cards, they also require them to be verified via a third party as genuine.
Westfields required their contractors to verify their operatives IDs with a company that they nominated.
The contractors also had to verify the trade cards with the respective issuing organisations.
This was quite easy with the ECS, each operative had to log in to their ‘My ECS’ and email a copy of their card to the contractor.
With the CSCS scheme it was a little more involved, they had to get the CSCS people to email a copy of the receipt for the operative’s card.
One of the reasons contractors use agencies, is because they rely on the agencies conducting due diligence on their workers. Verifying cards and qualifications and obtaining references.