TLDR: real time ship transfer would cost more AND take longer than moving the ship yourself.
EDIT: the point I am trying to make is any delayed transfer is pointless because it doesn't meet the intent of a quality of life convenience feature. Real time would take longer and cost more than moving the ship yourself. Shortened transfer times are so short to be more a nuisance than convenience, and would still cost money.
MATH!
Furthest distance between two shipyards (excluding Jacques) is 914 ly. We know that we can't travel that distance directly through a straight line so increase it to be a little bit more conservative, call at 1000 ly across.
The FDL and corvette have jump ranges of approximately 12 light years in a combat configuration. We can't assume that the ship will always be able to jump the max distance so to be conservative use a 10 ly jump distance.
10 ly jump distance, 1000 ly total distance to travel, gives us 100 jumps. Jump time from jump to jump in one minute, but that doesn't take into account refueling or fuel scooping. Assume that it takes an additional minute per jump.
Now we have 100 jumps taking us 200 minutes so a little over three hours real time travel from one side of the bubble to the other.
Moving the ship with the transfer at real-time takes three hours. However, we have to get there first so the jump ship that we're using maybe has a jump range of 30 light years. Three times the jump range, one third of the transit time. The time for us to get to the place we want to go is one hour and three hours for the other ship to arrive for a total of four hours to get the ship there.
Under that circumstance it actually would be more effective (less expensive and less time) for us to fly the combat ship itself, therefore the real time ship transfer isn't viable.
Ship transfer half of real-time in this case it would take an hour and a half for the ship to get there after we've ordered it in, the total time from departing the ship location to getting the ship to the new location is now 2 1/2 hours. Compared to three hours if we flew our self, saving 30 minutes.
Even with half time transit it doesn't make sense to have that feature because even in the worst case scenario you only saved yourself 30 minutes of time but you had to pay to have the ship moved.
The assumptions used in the examples above are purposely conservative to demonstrate that expecting the ship transfer to be real time or even half time doesn't meet the intent of the added feature and convenience of a ship transfer service. Additionally, the above scenarios don't include other factors that can reduce travel time such as larger internal fuel tanks, FSD upgrades, jumponium, or the upcoming neutron star boost.
Where do you draw the line on convenience though?
It's no strawman to suggest that we get rid of supercruise for convenience sake. There are plenty of people that would like to get rid of that inconvenient and boring mechanism.
Some people would like an autopilot so they don't have to sit and be bored making 20 jumps to go from one side of the bubble to another. Should we implement that for convenience sake?
How about the upcoming multi-crew addition? It's been speculated that players will simply be able to all appear on a friend's ship, instant pilot teleportation. Is that too much convenience?
Eventually we may just use the galaxy as a pretty backdrop for all the gameplay. If we do it won't be Elite Dangerous any more, just a series of mini-games.