Yeah, but there is no tangible way to measure luck IRL.
How would a pickpocket even know if he was lucky?
I would contend, that indeed, perhaps the IRL pickpocket just knows how to maximize his luck.
Subjective though, no way to prove it either way.
It's a skill. A carpenter can make mistakes when he makes a chair. A good carpenter can correct the mistakes he makes and waste a minimum amount of material while creating a product that looks good.
Likewise, a good pickpocket can do the same and will have ways to handle getting accused of pickpocketing. There's quite a bit of skill involved in this. Knowing how to apply pressure with your body via a bump or the like while slipping an item out so it goes unnoticed. Doing that in a way that is natural. Being able to palm or hide an item so no one sees you grabbed it (or to move it around if accused so it seems like you don't have it if a guard asks you to empty your pockets). Sure there's an element of chance, but that doesn't mean there isn't a huge amount of skill.
How does a pickpocket know he is lucky? A good pickpocket has to be able to assess his potential targets. He AVOIDS being lucky, because that means he picked a target that was difficult. A common pickpocket wouldn't do that, because he knows that means there's a higher chance of getting caught. There's no reason to go after a tricky target...just go after an easier one. You'd only do that if for some reason there was a particular item that you needed. This requires a lot of learning to pick up, and certainly a pickpocket is likely to realize it if he made an error in the difficulty of a target, though possibly too late.
Skyrim's system honestly leaves a lot to be desired here. I don't think it would be that hard to have a form of approach either. Heck, it could be as simple as using something like the magic system. You equip a pickpocket ability, "charge it", then release as you bump into your target (or potentially just stand close for some abilities that are for some items). Abilities could be categorized by location "briast pocket", "purse", "finger/wrist", or less accurately be grouped by item type (necklace, keys, rings, gold, etc). I think the former would be better, of course. It wouldn't be too hard for it to factor in how you bumped into the person as an element of success. Perks in pickpocket could slow down time if you held a charged pickpocket ability among other things, making it easier to get off correctly.
Naturally, they'd need to have a way to plant items, but there's no reason why the menu system could allow you to hold any time you wished. Certainly for small items that wouldn't be THAT difficult, I think. As a bonus it would help to create a more immersive environment. Then pickpocket abilities could be equipped into a hand even if an item was already held there, signifying you were trying to place that item. Alternatively, there could be another system to flag an item in your inventory for placement, which would be trivially easy to program.
They could even have a chance of failing without getting caught or succeeding while getting caught. Overall I think the vast, vast majority of the time you should be able to fail or succeed without getting caught. If you do get caught and have no item, then they can't prove anything. If you get caught with an item you should be able to bluff and say they dropped it (persuasion check).
Honestly, I don't think they thought about pickpocketing much and it shows. It wouldn't be hard to have a more comprehensive system.