Lanefan
Victoria Rules
If A1 and A2 could delay their actions until A3's initiative, they can all flee together at that point; leaving B4 out of luck.But if everyone has the same speed, then we need to determine whether or not the group runs away as a group, or if some of the members can be overtaken by enemies who can react quicker, and the system the game provides for that is...initiative!
Hence the problem. To use the chase rules, you need to stop using initiative, and let group A (the chased) attempt to escape group B (the chasers).
Because initiative is cyclical, that means at any given time group A wishes to flee, there can be members of group B who have yet to act in the turn, or who could act before all members of group A could attempt to leave the scene.
If we have two sides in a battle, and due to initiative, it looks like this:
A1
B1
A2
B2
B3
A3
B4
Group A, being down one person (A4, who has just died, say), wishes to flee. By rights, everyone should be allowed to act and decide if they wish to interfere with the fleeing party, chase after them, or let them go.
If you were to simply dispense with initiative and say "Group A flees en masse", does B2 and B3 lose their turn to allow A3 to escape, when they could prevent it by say, making a Grapple attempt?
I've never personally been in a game where this would occur. What generally happens is, in order for a chase to even begin, every member of the fleeing group act before the pursuers, and be out of range of any pursuer actions that could prevent the flight (or the pursuers are prevented from acting due to some other circumstance)...unless everyone wishes to flee on their own and let the devil take the hindmost.
In this circumstance, you can see how individual initiative actively hampers such group actions. Now someone might say "well, the DM can just decide to let the players escape", but I never said group A was the players! What if group A are the NPC's? I have difficulty imagining a table where the DM can say "the bad guys flee, ok, let's start using the chase rules" and the players wouldn't immediately go "wait a second, I still have an action!".
Then, once everyone's on the move it changes to [pick your pursuit system here] along with maybe some missile fire.