Couldn't you also say, "Az autóban a táska van"?
Your sentence means something else. The DL sentence means 'on' the car; your sentence means 'in' the car.
Értem. Köszönöm szépen! :D
Can’t ‘van’ come immediately after the subject?
In some sentences, yes, but here you would not want to. In Hungarian, you want to place the newest or most interesting information (it is on the car!) before the verb.
Why does it require "van" while in some of the prievous excercises "to be" in the third person was marked ad wrong?
The 'van' is omitted in statements of identity, but not in statements of location, etc. (Statements of identity may involve an adjective (he is tall) or a noun (he is a postman).