Are size modifiers relative?

In D&D 3.5e, size modifiers are as follows:

• Fine: +8
• Diminutive: +4
• Tiny: +2
• Small: +1
• Medium: 0
• Large: –1
• Huge: –2
• Gargantuan: –4
• Colossal: –8

These size modifiers are applied to a creature's attack bonus and AC.

Are these size modifiers relative to a Medium creature? For example, if a Tiny creature attacks a Tiny creature, do they both get a +2 bonus to their AC? It makes sense that a Medium creature would have a harder time hitting a Tiny creature, but I don't know why a Tiny creature would have a harder time hitting another Tiny creature than a Colossal creature would have hitting another Colossal creature.

The modifiers are static, and make attacks relative to each other appropriately adjusted for the situation. The equation bakes the advantage / disadvantage of size modifiers into base stats, and makes no impact on two creatures of the same size fighting each other.

These size modifiers are applied to a creature's attack bonus and AC.

Using the idea of equivalent equation, the size modifiers automatically take relative sizes into account.

For example - two tiny creatures duking it out are effectively at +0 size modifier against each other. +2 Hit, +2 AC VS +2 Hit +2 AC = total of zero modifier relative to each other. So they are on equal footing size wise.

A Colossal creature Vs a tiny creature

+2 Hit, +2 AC VS -8 Hit, -8 AC = +10 modifier in favor of the tiny creature. No need to re-apply the bonuses a second time.

A colossal creature VS a Colossal Creature

-8 hit, -8 AC VS -8 hit, -8 AC = total of zero modifier in relationship to each other.

A Gargantuan Creature fighting a tiny creature would be at a total + 6 modifier, and a Gargantuan creature fighting a medium creature would deal with a +4 modifier.

So it scales and auto scales. The math is already worked into the base stats of the creature to prevent excessive calculations during combat.