And many do not.
I have yet to purchase a Shimano crankset that comes with the BB.
The reason is that Shimano has no way to know which BB your frame requires, so packaging BBs with cranksets would result in people complaining that they have to pay for something they won't use. Far easier just to sell them separately.
Just bought a new SLX crankset that came with a BB. BTW, the chain is 10 speed ("10S"), not 105.