> The European Standardisation Bodies CEN, CENELEC and ETSI (independent of the OMTP/GSMA proposal) defined a common External Power Supply (EPS) for use with smartphones sold in the EU based on Micro-USB. [...] Apple, one of the original MoU signers, makes Micro-USB adapters available – as permitted in the Common EPS MoU – for its iPhones equipped with Apple's proprietary 30-pin dock connector or (later) Lightning connector.[1]
Nonetheless, framing ones' opinion of Apple's sustainability practices on this one pet issue seems quite myopic. The actual sustainability complaint stems from the alleged poor durability, not the choice of connection; but even if we accept that criticism, replacing charging cables occasionally seems like small drop in the bucket vs. the company's environmental impact as a whole.
1. https://en.wikipedia.org/wiki/USB#Mini_and_micro_connectors