mileage question

I first have to write that I am not a driver yet and am here to learn before going to CDL school.Im thinking about long haul driving and am confused about mileage.Some have said they drive between2000-3000 miles a week on average.I am aware that there are limits of 11 hrs per day and 70 per 8 day period.Some say your "actual" day can be more like 14 hrs.I drove from RI to Fl(1500 miles) in 27 hrs total.15 first day then 12.All driving safely and following the speed limit with good weather,bathroom food and fuel stops and no big traffic snags.If I did this in 1500 in 27 hrs,thats averaging 55 mph.If I am payed by the mile, 10hrs a day/7days in a row actually driving,that could equal 3850 for that week.What I dont get is where are all the delays a trucker experiences versus a passenger vehicle?I understand a truck may not average the same miles traveled per hour(acceleration for one),I dont know anything at all about how frequently you have to stop at weigh stations,fuel, etc.Can someone give me some input about typical delays where you are held up.I guess my real question is,what are the biggest time wasters a long haul driver has to deal with?(Im guessing my answers are somehow gonna be more complicated than I anticapate.Maybe a log book issue comes into play here)Thanks

 

ok,I understand that there are stops along the way and traffic.Whats the pre trip/post trip thing?Keep in mind I have not been to school yet.