Well on second thought the British had fought the French-Indian war successfully about 40 years earlier. I’m not sure of the the tactics, but you’d think there’d be plenty left alive to know how to fight that way. It might have been politics or it might have been that those who were there didn’t stay in the military. Hard to say.
If you read about the Siege of Badajoz, from the Peninsular War, which General Pakenham and his troops came from, you will see that there were times that these head-on assaults did win, even against dug-in troops, in this case French. Yes there were tremendous casualties but the objectives were accomplished. Of course every battle is different and the same tactics that win in one place can do you in in another.