Right plant in the right place has keeps us very busy over the years. But this is why it is a small market. Some high end residential could WANT a tropical landscape around the pool as a example. The right client understands you pay to play.
Yes, I have to agree freezing temps for several hours damage will still occur even with frost cloth.
If One of my customers wanted a little plant covered when I was already on-site. No problem
Of course the HO pays for the materials. But professionally I would think the company providing the frost protection service would purchase and store materials and bring the right "tools" for the job and bill accordingly.
However, for a small market we have been having the HO pay for materials and store them on site. Making it a simple for us.