Not sure where you are seeing those position, but in general, 99% of opportunities are a partnership track. I do see a trend with large practices not offering ownership within the practice. Most times, this is because the actual cost of a buy-in would be so large, it would not make financial sense. In doing so, practices typically offer incomes that would equal a partner. Many have started to change into a more corporate structure with voting rights but without the ownership option.
Hope that makes sense.