Doco:

Unfortunately you're speaking in absolutes, and you should not be.

Fact: the 48" bulb comes both as 54w and 28 watts.
Fact: not all T5s are HO.
That all T5 bulbs are HO, even for 24" is incorrect.

T-5 Lamp Miniature Bi-Pin Base 48" 6500K: Light Bulbs Etc, Inc.

Misinformation indeed.