I can't speak for all designers, but there are several reasons I don't distribute plans electronically.

1: Not everyone has AutoCad or a similar CAD program that can handle the files.

2: Not everyone has a printer which can output 24" x 36" drawings.

3: Electronic files are just way too easy to copy. Most of my customers are honest and understand I am trying to make a living, but all it takes is one person who doesn't think it would be a big deal to email a DXF file to a buddy or two, and suddenly there are free copies of my designs floating around. At least with the paper copies they need to go to a copy center with a large format copier. I choose to make it a little harder to copy to help protect my business.

: I also have worked as a surveyor, so I know exactly what you mean. I was not
: suggesting that plans are overpriced just suggesting that there may be a
: better means of delivering them. Where I work, engineering and survey
: drawings are never sent on paper anymore, always as computer files by
: email.