I agree with the previous poster. Disney transportation is, for the most part, very good and reliable. The 45 minutes you read is IF you just missed a bus and have to wait for another one. For the most part the buses run smoothly and you are rarely on any bus more than 20 minutes or so, normally less than that.
To answer your question about taxis, they are available outside the main entrances of all Disney resorts. They are normally waiting there but if not then the Cast Member at the outside podium will call and get you one right away. I have read that there are plenty of taxis avialble at Downtown Disney and Pleasure Island.