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What's stopping everyone from adding wireless charging? Google and Moto had it and dropped it. Apple added it recently. Etc?
Qi adds weight for coil and shield, and limits what material can be used for back surface that's also tend to add weight. For example, iPhone 8 added Qi and switched back surface material from aluminum to glass. 7 Plus is 188g then 8 Plus is 202g. It's not easy decision to have Qi for lightweight oriented device.
Are you sure? My wife has an iPhone 8 and it doesn't charge in our car which has wireless charging in the phone tray.