Yes, there are 401k's at both ends of the spectrum. The fees are a total of asset based fees and administrative charges, and your company selects from brokers that slant the fees either way. The fidelity website http://apps.fidelity.com/fescoPublic/cpr/preLogin.html
has a link to how to evaluate a 401k offering (for companies doing the offering) and notes that typically 91% of plan fees are asset based and 9% are administrative costs and goes on to discuss it.
So you get a better or worse 401k depending on if the company wants to foot some admin costs, or selects a plan where the participant foots more of the costs.