Banks should ask, you're trusting them with your money. People get so uptight about its my money, why should I justify it bla bla... and I get that to a degree but who actually cares when it's to help people. Don't use the Banks if it means that much to you.
i remenber refusing to serve a lady Who wanted 10k out to buy a car. She had all the evidence but I wa able to see it was a scam. Followed banking protocol and phoned the police. That woman would have lost 10k if I hadn't asked... even with the police talking to her she still took a while to realise what was happening. People don't like to realise they're a victim. Banks also have to repay a lot
Had another customer, who had a scammer on his mobile phone telling him what to say, a vulnerable elderly gentleman being scammed
Another lady tried to transfer a huge sum to her solicitors for her house mortgage deposit, only she had the wrong details where a scammed had sent new ones.
People might not like being asked, but it's worth it to save the people who are at risk in my view
Be honest about building works, the worker won't care. They'd likely ask which company and what you were having done... just to see if you seem genuine. if you say nothing and still want money, this is fine but you'd be made to sign to say in the event of being scammed its your own fault