Up until recently almost all trees were planted too deep, now only most trees are planted too deep.
With a tree that is planted too deep, the roots will grow up towards the surface, then turn one way or another. This is the problem, if the root turns and passes the trunk it will begin to increase in diameter atr thte same time the trunk is getting bigger. As the two impact, the root can choke off the tree. This all takes time. Just enough time for the tree to become a nice size where you really like it. A long enough time that the landscaper that planted it is long forgotten. In many cases the tree top begins to die off, other times the whole tree dies.
THe tree should be planted with the soil at the trunk flair. Go look at a tree that grew naturally, look at how it flairs out at the ground. Now go look at almost any newly planted tree, see how it looks like a telephone pole, going straight into the ground?
Learn what a graft union looks like. Don't confuse it with a trunk flair. Plant all trees with the soil level at the trunk flair. This means, in most cases, you will need to open the top of the ball and carefully remove the extra soil until you see the trunk flair. Some trees come from the nursery 14" too deep, but 4" to 8" is what I have typically seen. In extreme cases, by the time you remove all that soil, all you have left is a little tiny bit of roots and you need to stake the tree to keep it from falling right over.
It makes you feel like you got jipped and you did, because roots are a big part of what you pay for when you buy a tree. They make you think you are getting a big root system and all you are really getting is problems down the road, from girdling roots.
As far as time goes, typically, trees 15 to 30 years old die from planting depth problems. They could last longer, or are weakened and die almost immediately.
Hope this helps.