Q: Why do so many cellphones look the same, even when they are from different brands?
A: There are several reasons why so many cell phones look the same. To start with, many of the cheaper smartphones, especially the ones that have a seemingly powerful set of features, at a ridiculously low price, are mass manufactured in the same factories. Some features are adapted for local markets, but generally the handsets will look very similar, with only the brand name being a significant difference.
The second reason is that some smartphone manufacturers also make phones on behalf of other brands, examples being Alcatel manufacturing for Vodafone and Vodacom. The low cost of the resultant phones is precisely because no additional research and development, or design, had to go into the production of the devices.
The most important reason, however, for so many phones looking similar is that there are only so many formats that one can use for a smartphone. Further, they are only so many places where one can practically or logically place elements like selfie cameras or rear camera arrays.
Along with these factors, handset manufacturers always look at the best current technology and the best current practice in building a smartphone. The result is that most new phones evolve from what is currently on the market or about to be launched.