Can I use GPL, LGPL, MPL licensed packages with my application and make it closed source?

Question

I saw a company is using BusyBox and also using Gpl + Lgpl + Mpl packages on it, and then they have there own application running on it. Their application is a closed source package.

You buy the device but its closed source. How come GPL mixed with LGPL+MPL becomes closed source?

I thought the rule is?? Or I am wrong or this following info is wrong?:

GPL: If you use it in your application then you must release your application under the GPL. That doesn't mean you can't also sell it (like they sell Linux CD's) but you must also release the source code for free. That might work for you, but probably not.

LGPL: If you use it in your application then you can still have a closed source proprietary licensed application. But if you modify the LGPL library then you must release your modifications under the LGPL, even though your application can remain closed source.