We never give estimates without meeting with the client in person. Even if I could see their entire property in perfect detail over Google Maps (which isn't possible), I wouldn't do it.
The reason is that we don't win jobs based on price. We're more expensive than most of the other LCOs in town. If someone is just calling various companies, trying to get an idea of prices, they are price shopping. We're not going to win that game. So it's a total waste of our time. If they are not willing to spend 30 minutes with us looking over their property together and going over our various services, then we're not going to give a proposal - period.
We win bids when clients can meet with us in person, get a good feel for us personally, our appearance (our trucks, uniforms, business cards, estimate forms), how prompt we are, how comprehensive our service is, and we have some time to impress upon them that we really know landscapes. Give me 30 minutes with a customer and there's a 50-50 chance I'll land that account. But if we give a price over the phone, it's more like a 5% chance.
If we get calls or leads like that, we just explain to them that we only give estimates in person and would love to meet with them. If they don't go for it, we wish them the best of luck and move on to another call.