Why do players objectively get better value on SR than on any other map?

I'm talking about per-win IP boosts.

As the name implies, per-win IP boosts grant players a flat amount (within a small range) of IP when they win. Unlike timed boosts. per-win boosts are clearly intended to provide a consistent amount of IP. However, in contrast to this idea, the specific amount gained varies wildly depending on map.

As the wiki shows, per-win IP boosts are worth about 80 IP on the Crystal Scar and about 140 on Summoner's Rift. Despite costing the exact same amount of RP, a boost on CS is only about 60% as effective as a boost on SR. Why is this? When players get per-win IP boosts, they should be able to expect to get a consistent amount of IP from those boosts, regardless of which map they're on.

But if boosts are standardized across maps, players can spam shorter game modes for more IP! Yes, but it doesn't matter. It still consumes one boost per win, regardless of whether it was a 20-minute win or a 60-minute one. There's a potential for abuse if timed boosts gave flat amounts, but not for per-win boosts.

The amount gained depends on time spent in-game. Longer games give more IP; shorter games, less. https://imgur.com/flrYedS Not quite. Those are the results of my IP boosts from Snowdown. If you look, the ARAM game in the top-left actually lasted longer than the SR game in the bottom-right, yet I received 35% less IP for the ARAM game. That difference is beyond simple variance.

Those were free IP boosts though. Don't complain about free stuff. Correct, those particular boosts were free, and it was a nice gesture. However, Riot still sells boosts in the store. There's even a sale on right now.

SR should give the most reward because SR provides the most revenue for League. It also takes up the most resources. I'm not saying that boosts on SR should be nerfed down to the level of the other maps. Boosts on the other maps should be buffed up to the level of SR, so that players aren't compelled to play a specific map if they don't feel like it.

Most people play SR anyway. Why is this important? Because it's inconsistent with player expectations. When a player has a per-win IP boost, they should be able to expect a certain amount of IP from it. With the current situation, they don't have that guarantee. RP is inexplicably worth 10-40% less while playing on maps besides SR.

tl;dr: Per-win IP boosts should be worth a consistent amount of IP. Unfortunately, your money (or time) currently is explicitly worth less on different maps. The value for your RP varies wildly depending on what map you're on.