You are correct that all roulette odds are the same with the exception of the 5-number split.

The roulette wheel design with 36 numbers (excluding the 0 and 00) was not accidental. 36 is EVENLY divisible by many numbers, which are used to calculate the payoff multiple: 1x36 (single number bet); 2x18 = 18x2 (red/black; odd/even); 3x12 = 12x3 (first/second/third 12's and first/second/third columns); 4x9 = 9x4 (corner bets); 6x6 (split row/6-way bets).

If a roulette wheel eliminated the 0 and 00, and the payoffs were not changed, it would have no statistical advantage. The added 0 and 00 gives the house its advantage.

BTW, the reason the 5-way bet is worse is that payoff is rounded DOWN (in the house's favor) to 7-to-1. 5x7=35; whereas all other payoff multiply to 36.

(I'm simply restating the same points others have made, but thought the underlying math might be helpful.)