Sorry, but you talk (sorry to say) bulls**t.
At most big banks (Intesa, Unicredit, OTP...) have branches in Belgrade where minimum one person has focus on foreign customers.
Open an account is so easy. You need only your passport, the white paper (registration from your hotel at police), proof of address (for example bank statement of other current account) and half hour time - thats all. After half hour you have your multi currency account (Dinar, EURO, Dollar....) and online banking.
Of course you can transfer between your own accounts at same bank without additional costs and for transfers from and to Serbia you will use SWIFT - so simple, so easy.
Also "
cash in" is for free - only between 500 and 600 Dinars maintance every month.
Oh - of course you get cards - for example Mastercard Platinum and Dina Card (for local payments in Serbia)