For airlines that use the piece concept, I can't find another example of which standard economy ticket can check 2x23kg bags
(at least not for BA, <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}-->Lufthansa group and NZ, you always need to pay to check additional bags)
In this part, I would say CX is being generous.
An advantage of the piece concept is that when your additional bag weights near the limit, it will be cheaper than with the total weight concept where excess weight is charged per kg