What do you make of sellers who only want to converse via email?

Is it asking too much to speak on the phone about an item that the seller has for sale on this forum?
Specifically, big-ticket items like engines and transmissions that are hundreds of miles away from your location.
I don't understand the reluctance from a seller to speak on the phone about something that the seller has listed for sale.
Especially, when you are prepared to drive hundreds of miles and spend hours on the road to pick up the item.
The seller is a known member and has been on this forum for years and actively post parts all of the time.
Please let me know if I am expecting too much from a seller