Lawrence, your statement is only partly correct. I just discovered this problem today when receiving photos in Yahoo web-mail using a Chrome browser, and found this thread, which seems to have evolved into more recriminations than solutions.
In some technical sense all photos are attachments because all attachments are encoded information that is included in the email packet in some form. BUT, there really is a distinction both for the end-user experience and in the actual MIME encoding in the message for "in-line" images versus ones that typically (when sent using other non-ios systems) show up as listed attachments for the user to save.
To illustrate this, take a look at this extract from the "raw email" containing several images -- note that the encoding is, yes, described as an attachment (as all MIME and similar content is) but is ALSO described specifically as "in-line"! The in-line display is not just arbitrarily chosen by the client software: the image was specifically labeled to be displayed in-line by the sender's iPhone.
--000000000000ad33ff05caf45d68--
--000000000000ad340005caf45d69
Content-Type: image/jpeg; name="IMG_2994.jpg"
Content-Disposition: inline; filename="IMG_2994.jpg"
Content-Transfer-Encoding: base64
Content-ID: <17ba2e831f8e5828e8f2>
X-Attachment-Id: 17ba2e831f8e5828e8f2
/9j/4Ql2RXhpZgAATU0AKgAAAAgADgEPAAIAAAAGAAAAtgEQAAIAAAAJAAAAvAESAAMAAAABAAYA
AAEaAAUAAAABAAAAxgEbAAUAAAABAAAAzgEoAAMAAAABAAIAAAExAAIAAAAHAAAA1gEyAAIAAAAU
AAAA3gE8AAIAAAAJAAAA8gFCAAQAAAABAAACAAFDAAQAAAABAAACAAITAAMAAAABAAEAAIdpAAQA
AAABAAAA/IglAAQAAAABAAAIcgAAAABBcHBsZQBpUGhvbmUgOAAAAAAASAAAAAEAAABIAAAAATE0
LjQuMQAAMjAyMTowOTowMSAxMzozMjo0NwBpUGhvbmUgOAAAACOCmgAFAAAAAQAAAqaCnQAFAAAA
AQAAAq6IIgADAAAAAQACAACIJwADAAAAAQBQAACQAAAHAAAABDAyMzKQAwACAAAAFAAAAraQBAAC
AAAAFAAAAsqQEAACAAAABwAAAt6QEQACAAAABwAAAuaQEgACAAAABwAAAu6RAQAHAAAABAECAwCS
AQAK ...
The Base64 encoding goes on for pages and pages.
I have not had this problem of images not even displaying in-line with anything other than some sent from iPhones. I can see that there *IS* a JPG file, I just can't VIEW the JPG. If I can view images from other people, then yes, this is an APPLE problem.