contract costs

Professor, my text states that general overheads and waste materials are expensed to SPL and not categorised as contract assets, because to qualify as contract asset the costs should be incurred in fulfilling the contract and they should be either explicitly recoverable under the contract or implicitly recoverable through a margin.

So don’t you think that when deciding on a contract price (and margin) the supplier will take into any general overheads and costs of any potential wastage of materials? which means its recoverable and hence should be capitalised?

I know its a revenue expenditure so as per F3 rules we will expense, but my bone of contention is with respect to provisions of IFRS 15. It will be great if you can falsify my claim on a rational ground.