All of my recruiting work was retained for the last 5-10 years I was in business, and I wasn't recruiting executives. I'm not saying that is the norm (it definitely isn't), and you are correct that senior developers will not be approached for executive roles.
Higher level candidates will probably attract higher level recruiters, because the amount of time to place someone making $100K is the same amount of time to place someone at $500K, with the only difference being a $25K fee for the first person and a $100K fee for the second.
Higher level candidates will probably attract higher level recruiters, because the amount of time to place someone making $100K is the same amount of time to place someone at $500K, with the only difference being a $25K fee for the first person and a $100K fee for the second.