Exactly and that's why the teams that do go testing probably aren't so keen on others using the windtunnel instead.
The proposal by Sauber and Force India is fuelled by self-interest too.
The teams can't even agree on what day it is and it has always been like that.
Teams should look after themselves that's what they do best.
Others such as FIA and the commercial rights holder should worry and take care of the health of the sport.
Oh, Sauber will be wanting an option that suits Sauber. But there's a difference, to me, between wanting another solution, and demanding just one, as long as it suits. Which isn't to say either team is acting selflessly, because none of them seem to care about anyone other than themselves.
A certain sexual kinkster tried to argue the teams need to be told, not asked, what to do, and look what happened to him. Which is why we have this continuation of the teams all falling over themselves to protect their advantages, undermine those of others, and mostly maintain the status quo even though it's given us near spec cars, stagnating oily bits, and gimmick laden crap that even Nascar would probably find artificial.
We really do need someone to step in and say "You can have much more technical and sporting regs freedom, but you can only spend x a year, so shut up with the "Woe is us, it'll cost too much" and get on with it". Red Bull can Newey their backsides off, Ferrari can have twenty drivers hammering around their private track, and Sauber can wind tunnel morning noon and night, as long as none of them go over budget. Different answers to the same problem, so the brains flex more than the questionably legal wings.