I know the metric system is probably superior, but it’s not my fault I was born in the USA. and use the imperial system.
20xp/km and 30xp/mile
1 km is 0.621371 miles
1 mile is 1.60934 km
20 x 1.60934 = 32.1868
So why not 32xp/mile?
100km = 2000xp
62.1371 miles = 1864xp (136 less XP)
62.1371 miles = 1988xp (only 12 less XP)
To reach level 50 you need 500,000 XP. Assuming only getting XP from distance (no bonus xp awards) you need to ride 25,000 km (which is 15,534 miles). However, to get 500,000 XP on the imperial system you need to ride 16,667 miles or 26,823 km. 1,823 km (1,133 miles) more than someone on the metric system.
At 32xp/mile you would reach level 50 in 15,625 miles. 1,042 miles less than the current system, but still 91 miles (147 km) more than someone on the metric system. Not perfectly equal, but so much closer.
I know I can just switch to metric in the game, but I track IRL distance in miles, so why track indoor Zwift distance differently? It should just be more equal and fair on Zwift.