I hope you also recognize that it's really important that no one feels any compulsion to consent to students when they don't actually want to. There should be no pressure and no chiding of people who say no.
I completely respect the service user's right to refuse. If anything, I'd actually expected more people to utilise it. I actually very much object to the lack of transparency around it.
I recently discovered that there was a student midwife involved in DD's delivery. This isn't something I should only be finding out when DD is 4
I've also given feedback to a few of my placement areas that parents shouldn't be finding out that their child's nurse has a student with them only once they're on the doorstep. It puts people in an awkward position.
That said, I also realise that HCPs do have to learn somehow. It's better that this happens at a point where people know we're learning than when people see the uniform/ID of a qualified professional and simply trust that we have enough experience and knowledge to manage their care.
People refusing our involvement is likely to be less of an issue in a hospital setting (plenty we can be helping with usually) but when the alternative is us sitting in the office, I can understand why nurses in community services and clinics are reluctant to inform people ahead of time that there will be a student with them.
Not that I agree with it, I really don't. I've actually willed some parents to refuse my involvement so that I had to sit in the car during a visit, enabling me to really drive my point home.