Why people don’t want to conduct business from Special economic zone even if they are eligible ?

I have seen many of the businesses that are eligible and also can get approval to conduct business activities from SEZ but still prefer to conduct from the non-SEZ zone. So what is the real reason behind this?

Because they will be getting full tax redemption on income tax no MAT, and no import duty then why people still don’t go this way? I want to know hidden things about not adopting this route