There is a theory that regular auto transmission fluid is bad for the joints. Whether this is true or not it is the wrong type of fluid for the power steering on our cars.
The MR2 power steering is electro hydraulic and so the fluid has very different characteristics.
I believe it is a similar difference to that between brake fluid and engine oil i.e. one type is intended to lubricate and the other is intended to do work.
Whatever is actually true, the fluid should be a golden colour. If it is red then it is wrong. Peugot are a big user of electro hydraulic fluid as well. You can get a smaller bottle with them for less than Toyota.
Some info here ... en.wikipedia.org/wiki/Power_steering