Well, I'm French and have a much easier time with spelling in English than in French... Joke aside, I guess having multiple sequence of characters map to the same sound have more of an effect on making spelling difficult.

While I think that indeed a given sequence of characters is generally pronounced the same what is confusing for children is the plethora of consonants that are not pronounced. So ils chantent and il ment. écoles et les and so on... There's also the liaisons that adds a lot of confusion between what's written and what's actually pronounced. But maybe you're right and this is more of a problem in English.