> 1. Have two "i" characters on Turkish keyboards, one to use when writing in English, one in Turkish. Sounds difficult to get used to. Always need to be conscious about whether writing an "English i", or a "Turkish i".
But you have to do that anyway to be able to produce the correct capitalized version: an "English I" or a "Turkish İ".
No: a Turkish keyboard has separate i/İ and ı/I keys, and Türkish-writing users with an American/international keyboard use a keyboard layout with modifier keys so that the i/I key can be altered to ı/İ. (I do the latter for idiosyncratic reasons.)
The person you're replying to is pointing out that differentiating English-i from Türkish-i requires some other unwieldy workaround. Would you expect manufacturers to add a third key for English i, or for people with Turkish keyboards to use a modifier key (or locale switching) to distinguish i from i? All workarounds seem extraordinarily unlikely.
Yes, there are two keys, but their function is not to write the character as a "Turkish i" and an "English i". These keys are necessary because there are 4 variations, that need 2 keys to write with caps lock on and off:
Key 1 - Big and small Turkish "I": Caps Lock On: I Caps Lock Off: ı
Key 2 - Big and small Turkish "İ": Caps Lock On: İ Caps Lock Off: i
For small "Turkish i" and "English i" to be different characters, there would need to be a third key.
But you have to do that anyway to be able to produce the correct capitalized version: an "English I" or a "Turkish İ".