Some laptops do have user upgradeable graphics, but it is usually on top line models, especially gaming specials and boutique exotics. Here is a more modest Dell E1705 (equivalent to the UK Inspiron 9400, I think), being dismantled to upgrade the graphics.
I was careful in my choice of words. Normally you cannot upgrade graphics, but in a few models you can. It is inaccurate to say that none can be upgraded.
yeah, unless you get a 3000$ gaming notebook, on 90% of laptop you cant change the gfx chip