Ive noticed that as well Thats actually what confuses me the most If it really is a single why cant I buy it anywhere Honestly I think that if people write it as a single they dont really care if it isnt available separately simply calling something a single doesnt specify whether its promo or not For people trying to cater to consumers like Billboardcom reviews if its a popular hit andor music video people know it it doesnt matter under what technical details it was released But I think the difference is that since we are able to specify this we probably should We should try to reflect the reality I dont think having a music video and a high placement in charts does anything to change the type of single it is Ive seen music videos for promo singles many times before even some for album tracks Isnt it a promo single nevertheless if its only available separate from the album for promotional purposes Its not like this is degrading the single in any way either some artists just dont release subsequent album singles separately for consumers because theyd rather prefer they buy the album