I don't know the actual nitty gritty details. Smaller 401ks can be expensive to manage. Our company is about 80 employees, and our 401k fees are pretty high.
On top of that, we don't match. And *most* of our employees are highly compensated. (not me. wheeee.) But I'd say that probably 60% are because it seems like we are mostly directors and above.
That means, since we don't match, that the highly compensated employees are limited to the amount that they put in. I'm not sure of the number here, but at a prior company it was 4-5%.
I'd imagine that if you add up the fees, then figure that the doctors are either limited to putting in a few percent *OR* they have to do a company-wide match, they would consider it too costly.
The total amount put in by HCEs (average) cannot exceed that put in by non-HCEs (average) by more than 2%.
If half of your staff is making $200k and the other half $35k, you can see the problem.