NYELVÉSZ

Yes, the meaning of "meaning" is essential in this case...

I had given some thought when I wrote the sentences in past tense separated... originally I used the '[i]because[/i]'-linked form

I thought that the two versions have the same meaning informatively, I mean the ('because'-)sentence in past simple expresses the same information as the third-conditional one - apart form that the third-cond. one has an 'background' meaning that refers to intention, just like Pres. perf., that refers to the present, I mean the result in the present. E.g. "I have come" means "I am here", too.

I think it is only approaching the same meaning from different directions. The situations in which these forms appear usually specify how the forms / structures has to be meant. I had this in mind, when I thought of "the same meaning".

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"Le a 'LY'-vel, é'jj'en a 'J'!"

Strictly speaking the past simple example doesn't "have the same meaning" as the conditional sentence. Of course, this depends on how you define "meaning"... "Officially", so to speak, the causal relation is only implicit in the two-sentence version, whereas it is explicit in the conditional (counterfactual) sentence. In the former, the rhetorical relation between the two sentences (namely, that the content of the second sentence serves as an explanation for that of the first) is left implicit. You come closer to the meaning of the conditional sentence if you make the rhetorical relation explicit, as in I didn't go there because I had no time. But I have the impression that even this version is not exactly equivalent to the conditional sentence.
Different structures convey different messages.

About 10 years ago I had an argument with the main admin of englishonline.hu.
I told him that past simple has the same meaning as third condition with its opposition, I mean:

"I didn't go there. I had no time." = "I would have gone there, if I had had some time."

I told him that the sentences in the past simple have the same meaning as the sentence in the tird condition. In my opinion maybe it is more practical to demand easier structures with the same (direct) meaning from students, or it would be necessary to show them that certain structures have the same, almost equivalent meaning.

I've also found a lot of tructures in English that are short forms of longer structures - but grammatical descriptions never tells about them. I think they would be learnt and taught in an easier way...

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"Le a 'LY'-vel, é'jj'en a 'J'!"