If a CPL is considered an NCO, then why don't they receive NCOERs?

They SHOULD receive them. NCOERs for CPLs don't count, they don't go on the record. But they should still get NCOERs to get them used to what they look like and the process.

You'll find an answer in a question on this topic posted a few years ago. Here is the link:

https://www.rallypoint.com/answers/do-corporals-receive-ncoers

Because CPL E-4 and SPC E-4 promotion requirements are the same and because CPLs haven't attended BLC so can't be held to a standard they haven't been taught. NCOR's are to help determine promotion and to guide an NCO to meet their rank duties, but mostly to see who is fit to be promoted and since E-4 to E-5 is the same requirement to promote irrespective of SPC or CPL it would be unfair. They already are do an E5 job at E4 pay....why add more BS?

CPL or Spec 4's are not. Not many CPL's in the Army. Marines are alot. I don't even think the Marines have Spec 4's.

That is a good question to ask I have asked several times back in the early 80s when I was promoted to specialist and I was wanting my Corporal stripes so I finally got them and you have the duties as an NCO but not the payroll if that makes sense and yes, I agree that corporals and E4 specialist is the same rank but the specialist is only specialized in one field only I was not specialized in one field. I had multiple MOS is and multiple positions.

I never received one as a CPL

As it went back in the day 88'-93'(my days) CPL rank was earned as there were a lack of team leaders/NCO's and the promotion points for us stayed at 993 to make SGT was they were weeding out NCO's that stalled out with 10+ yrs time in grade. I stayed E-4(P) for 4 years, I qualified expert in ALL areas weapons both .45 and 9mm, M-16A3, German Shutzensnuer silver award to include PT fitness excellence award, wheeled and tracked vehicle driving awards and did kick-@zz on the board from what Top told me anyhow. I was going to be a lifer but my wife at that time wrecked that for me. It was crazy situation at best brother.

They can receive ncoers but it’s not required.

What is a NCOER?

You have a valid point and perhaps DA needs to address this issue. Currently the following applies per AR 623-3 NCO Counseling Requirements.
"The DA Form 2166-8-1 will be maintained for each rated NCO until after the NCOER for that period has been approved and submitted to USAEREC. For corporals, who do not receive a record NCOER, the rater will maintain the checklist for one year."