Sadly the issue of tailgating never goes away (as Simon points out). Some residents value their 20 second faster exit more highly than their fellow residents valuables. Unfortunately revoking access would only be legally enforceable against tenants and not leaseholders – and then only if their sub-lease allowed for this.
Longer term residents who ignore the issue are never going to change and hopefully they are in a tiny minority (maybe when the CCTV is up and running we can 'name and shame' on the website and twitter for all to see!) – newer residents may not be aware of the issue and so perhaps a small leaflet reminder on cars every few months may be helpful.
Fingers crossed working CCTV will be a deterrent once people are aware that it's live.