With a single class of shares every shareholder interest is aligned. It is not possible to create a subclass of shareholders among the existing shareholders without existing shareholders agreeing to it. So in a buyout all shares are equal and will receive and equal percentage of distribution of all assets regardless of how those assets are structured.

The moment there are different classes of shareholders, there's a jockeying for a position. It is no different from the plays that can be made by a private company when it is getting a new round of investment/gets bought out -- those with A class shares have certain rights, with B some other rights with C some other rights etc. There's nothing ( apart from a rather complicated regulations that govern a right of minority shareholders not to get totally screwed ) that prevents those that control the voting block via special preferred shares from virtually screwing other shareholders:

Board can just vote to split the company into "icky carcass" with nominal assets, most of the liabilities give most of it to non-voting shares. Give the non-voting shares some tiny percentage of the ownership in the "awesome sauce" part of the company. Voting shares (held by insiders) get the opposite percentage. As the part of this deal the "awesome sauce" company gets sold.

It just has not been tried yet -- in fact I'm very surprised it has not been tried yet. It of course would be challenged in courts but I'm pretty sure it will be found legal -- after all "you have no rights compared to the rights of holders of class SP" has been spelled out in the offering paperwork and investors/employees/shareholders still lapped it.