i pay 1400 people a week. less than 5% of them are in the company pension, they rest either opted out (very high opt out rate and a very small % are not eligible.
I highly doubt the 95% have private pensions, some will, most wont.
On our monthly payroll, i can count on 1 hand the amount of people that put in a higher than basic %.
People are just not planning - mostly because they want the money now, not in the future.
In my role, i don't see people seriously planning until they are in their 50's, by that i mean at bonus time, the over 50's tend to put half or more in their pension and get the tax relief on it, but the younger ones aren't. Could they be putting it in to a private pension? Maybe. But unlikely.
I only do the basic, i have about 8 pension pots sitting in different providers from different auto enrolement schemes. One day i may bother to look at them all but i never even think about it until i see a thread on MN.