But still, depending on the cost and the average number of packages, it could come out as a significant cost per order.
The core reason why shipping costs were pulled out separately is that it allowed the customer to choose between various options freely, if they needed it tomorrow vs. whenever. If there's no choice, there's much less incentive to do that.
However, there's still at least a little something I can think of; shipping is generally not part of the sales tax. Rolling it into the price means you're also making your customers pay sales tax on it. That depends on whether you've got to pay tax on the item in question, of course, which varies every which way.
Customers also have the option to upgrade to faster shipping if they so wish.
What worries me is the greed in human society, you have a company with profit but the leaders or shareholders want more and more each year, so when there is no more room for growing then someone needs to be milked harder and harder.