The shift from Apple's Lightning connector to USB-C on iPhones is primarily driven by European Union regulations aimed at reducing e-waste. The EU courts were concerned about the environmental impact of Apple's proprietary cables, which are not universal and only work with specific Apple devices.
USB-C has become the industry standard due to its faster charging and data transfer capabilities. It's already used in Apple's MacBooks and iPad Pros, making the company's resistance to adopting it for iPhones seem inconsistent.
The Lightning connector, while familiar to Apple users, has several drawbacks. It's less durable than USB-C, can get dirty easily, and tends to stay connected too strongly, potentially causing damage if accidentally pulled, which also was a reason for
the wireless charger MagSafe to come into existance.
Apple's reluctance to switch was likely influenced by the royalties it received from third-party manufacturers using the Lightning connector. However, the EU's 2024 deadline for USB-C adoption has finally pushed Apple to make the change with the iPhone 15, launched in September 2023.