1. Most people don't actually read long EULAs. And who can blame them? We have been trained not to read them, and if you do, you are spending a significant amount of your life on a tedious and frustrating endeavor.
2. If you do read it, it is a long document in difficult and intentionally misleading legalese, where you can easily miss something.
3. If you don't agree to the terms, and return it, does the company pay for the shipping? Even if they do, you have now wasted a fair amount of time on this product you won't actually use.
4. Depending on the product there may not be anything on the market that has an acceptable EULA. In part due to the fact that few enough people read the EULA that companies can afford to lose business from the people who do.