I think you're asking me a question about the inner workings of government, which would be far beyond me. But I can say this: deduction of operating expenses is a common deduction in any tax regime I've ever done business with in the world.
On the oil and gas front, what's called the Canadian exploration expense is typically either seismic drilling or exploratory drilling in wildcat areas or dry holes, dry and abandoned wells, which are typically written off as a total loss to the company at a 100% rate, again in almost every jurisdiction on earth that I'm aware of.
As well, in terms of the rate of deductibility of all other expenses, you talked about Canadian development expenses, which are deducted at a 30% declining balance rate, and capital cost allowance, which is typically a 25% declining balance rate. Those are very standard depreciation rates recognized across a number of tax regimes.
There are variations on how taxes are paid. As an example, if you drill a well in the North Sea in Norway, you'll actually receive a cash payment from the government equivalent to 80% of the cost that you incurred on that well as a return on your tax payment. That's something the Canadian government doesn't do.