you mean security of the driver, while on runs, or of the money collected? or both?
for the actual driver, cel phones are a must anymore. Cars in good mechanical shape, filled up with gas before the shift. Maps with them. Questionable neighborhood? Send 2 on it. Make sure they know, understand, and will act appropriately, that if they should be held up, GIVE THE MONEY UP NO QUESTIONS ASKED.
On those questionable runs, give them only enough change to meet the next bill–change from the ticket total to a $10 , $20, or $50 bill. If they’re running a bank for the night, make sure they drop after x number of deliveries or $100 sold. Car toppers are nice for advertising, but they sure do draw attention, good and bad. The bad is worth avoiding.
For the money, again, have drivers do a drop after x number runs or $100 sold. Manager and driver count the drop together to verify amount in it, then it’s put away. Driver signs a slip acknowledging the bank they start with, just as a server should. Manager calculates amount due at end of shift, driver double checks and counts it out, manager recounts before driver closes out. Keep the car toppers off the cars, they’re not worth the risk anymore.
my thoughts. YMMV