The only reason you can’t parallel park is because you aren’t following the directions to the letter. You think your car is too close, or too far, or too angled, and you don’t turn your wheel all the way, or you keep moving when the directions have told you to stop and turn your wheel. The directions for parallel parking (that you get from the DMV, or in your driver’s ed course) are actually very precise and if you follow them exactly, you will park your car perfectly every time. You do not need to practice, you just need to fucking follow the directions.
Since I don’t live in a densely populated area I’m fortunate enough to not need to parallel park much, but when I do I can feel the sweat on my brow. I’m one of those people who will drive around to avoid parallel parking. The last time I parallel parked well it was on the street in front of my college apartment. I didn’t want to move my car I was so happy with it.