Could this not be explained purely because of access to better funds? For example: Vanguard charges a higher expense ratio on the funds that are under $3000 in

Could this not be explained purely because of access to better funds? For example: Vanguard charges a higher expense ratio on the funds that are under $3000 in investment. Above $3000 you get 'Admiral' class with lower expense ratios. Even above that, there are 'Institutional' class funds that have an even LOWER expense ratio (with minimums of $5M). I imagine similar examples exist at other firms, companies, etc.