does vpn protect internet traffic in public wifi networks ?

[PhantomBandit670]

I recently saw a popular technology program on tv and they were talking about how unsafe internet traffic is in public wifi networks say in coffee shops and other places. Surprisingly the suggestion given by a security researcher who was interviewed was to use phone's internet connection and avoid public wifi, he did not even mention about VPN services.

I was curious to know why VPN services were not suggested as another possible approach to provide atleast provide basic level of security(ie., no bank transactions or purchases, but atleast some form of encryption method to hide/mask username and passwords from emails websites, from preying eyes).

I use Hotspot shield vpn, and thats how i try to connect to internet when im at hotels or at cofee shops.

Am i missing What are your thoughts?
well by 'some form of encryption' i meant encrypted private tunnel by using VPN service.