Enemy spawn safe zones

Has anyone else noticed how thw "safe zone", the area around the enemy spawn points where you can't place defenses, isn't a static distance?  Even on the same map it changes between the different lanes they have different spacing.  Wonder if someone will shed some light on this?

 At least on ps4 this is the case.

does it matter much?  I sure its all based on who ever designing the levels.

I'm sure it has a lot to do with AI/Collision detection. Better to just prevent bugs at the spawn points as needed than try to set a standard and work around it.

The only thing that bothers me a little is how some let your towers start wailing on them way before they pass that gate. It's convenient and all, but inconsistent.

For me it's an aesthetic thing.  It would seem to be easier of there was a static disrance and not a fluctatiing one.