Why did Allied landing-craft bows differ?

Why did British landing craft use different bow shapes from American and Japanese craft?

They were optimized for different beach materials, reefs, surf, and operating conditions.

British planners expected a mixture of shingle and deep sandy beaches in European waters. American and Japanese requirements placed more emphasis on Pacific beaches, reefs, and volcanic terrain. Designers therefore selected bow shapes for the particular shore and approach conditions their craft were expected to face.