I agree, my last role was 25+ public holidays. They also offered holiday trading, which is a real "benefit" that should be advertised in my eyes. That allowed me to go up to 30 days annual leave + public holidays which was great. Current job is setup as unlimited with a minimum of 20 + public holidays, all in all I take about the same as I did at my last place but it's a bit less hassle to track.
Advertising 20 days + public holidays in the UK is basically advertising that you give people the minimum the law will let you.