apples to oranges...running a resi service company, you may have 5 vans and 15 jobs a day for them to go to. You can't possibly give 15 estimates by yourself, and you really don't want to send a service truck to give free estimates at $3.50/gal +labor.
lets say you can do 4 estimates a day yourself (any more than that, and I assure you that you are leaving money on the table at each one)you work 240 days a year...so you provide 960 estimates a year (my guess is that is way more than you really do)...let's say you pay yourself $50,000 yr total package (yep, you work cheap)...and you spend 8 hrs a day giving those 4 estimates (including travel and writing the proposal)
each estimate costs you $52 in labor +fuel + wear & tear +overhead+ whatever else it costs you...you are easily looking at $60/estimate...if your average job ticket is $500...you immediately lose $60 off of that.
if you close 50% of your estimates, you have to immediately deduct $120 from every job you get. so now you are down to making $380 on a $500 ticket.
or you increase the price to the customer that hires you to $560 to cover the cost of the "free estimate"
either way someone pays....