It's not possible to get into a boat/minecart in survival mode being 4 blocks away from it, while in creative, it is.
In the test performed below, the entities are uniformly separated by three blocks. It will be possible to teleport from a boat/minecart to another in creative, but not in survival.
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Because it's creative mode.
All the distances for the player are way greater: Distance for placing blocks, destroying blocks, mounting horses, etc.
That's not a bug.