Advantages of a tailgate (hydraulic platform)
The majority of furniture removal trucks have ramps.  I have a large tailgate which also tilts.  It is a unique one-off design. 
It is aluminum which means it moves faster up and down than the heavy steel ones which normally require a larger truck to be able to take their weight and also due to the higher ground clearance with a larger truck would further  increase the time taken to move it up and down.
There are several advantages to a tailgate.  Obviously with an item which is very heavy such a piano, pool table, safe etc it is safer and easier for the removalist to take it up on the tailgate.
There are other advantages to.  Standing on the tailgate means the truck can be packed to the roof right to the back doors, something which is impossible to do with a ramp.  Rather than going up and down the ramp numerous times we can push items into the truck, there is no ramp in the way, load up the tailgate and then go up into the truck to pack. 
When unpacking smaller items can be spread out on the raised tailgate, especially beneficial when a client wishes to help and thus I can unpack onto the tailgate whilst my offsider and the client can take items inside.