There is lots of research showing that excessive screen time is detrimental to the development and health of children, and that follows them to adulthood.

There are lots of articles about it online, here is one :

http://www.med.umich.edu/yourchild/topics/tv.htm

Reading is more than practicing the skill of reading, your brain is more active than when just watching tv. The link above addresses that issue, as well as many other issues.

We watch TV in our house, but I consciously limit it and find that having it on while they play is unnecessary. I have found no need to have it on at drop off time in the morning or at pick up time with the daycare. The kids have no expectation of TV being available and just go off and play. If they are feeling tired or grumpy they go lay on the pillows and look at books. Most of the time I use it as a quiet time activity when I want the kids that don't nap to get some body rest and time of total quiet.

I also would also have expectation of little TV time if I was paying for someone to care for my kids. I would be disappointed to find out that the TV was on several times a day at their daycare.