How would you respond to these applicants?

[Summerishere123]

Would you even bother?
We have had several applicants for a cafe role. Some good, some not. I'm interviewing tomorrow.
I have had 2 applicants that sent a CV but nothing else in the email. No "please see CV attached" or even a subject heading in either. I have also had one that is clearly been done on the behalf of their offspring as their email is a "Sophie Smith" and the applicant is a 23 year old male with a different name and email address.
I know etiquette dictates I thank them for their time, but they haven't made an effort here have they?!!
I have seen this a few times, along with a recent trend of posting on random facebook communities saying "18 year old male looking for work will do anything". Really?? Who is telling these kids how to apply for jobs?

If you want to do them a favour, you could email them a polite recommendation that they take a more professional approach in the future. But at that age and for jobs like that they're probably sending in loads of CVs and mostly not getting any response so that's fine too if you don't have the time or head space.

Was it through a job hunting website like Indeed or Monster? If so I know cover letters are optional on those.
I always send a cover letter and do the " please see my cv for your reference" for jobs that require you to apply to a specific email address tho. The latter I see as good etiquette.
Depends how desperate you are to hire someone tho, if their cv looks good and is formatted correctly then I'd give them a shot.

Just write back a one liner saying we only accept applications with a covering letter

We always make a point of emailing all unsuccessful applicants (even if they sent in a rubbish CV like in your example.) Just a couple of lines "Thank you for applying for the role of X, unfortunately your application has not been successful. Best wishes for your job search."

I am always tempted to reply with the correct etiquette but it feels petty so I don't. The CVs are sometimes okay but to be honest, we don't need anyone super clever, just with a bit of personality as the cafe is attached to a play area and so we want happy bubbly staff. Those that cannot be arsed to even put a subject heading come across as the opposite.

When I was in this position, I only used to send “declines” to people who’d been for an interview, not to every single applicant.

Plus people who can’t read a job ad and respond in the way specified were automatically discounted. For example, if I posted an ad on our Facebook page saying to email us with their CV and people commented “Interested” or “PM me details” they were automatically excluded and not responded to.

I would reply to them with constructive criticism. I wouldn't use the word etiquette, that's not a very business-like term. I would just politely explain that they are going to make better progress by adding something relevant in the subject line, including a short polite message with the CV, and send it from their own email.