There’s lots of people outside. There’s a few things I’d like to discuss with you. There’s too many sentences in this paragraph. Those are all sentences you might hear native English speakers say. You might hear me say them.
There’s followed by a plural noun phrase is found in non-standard dialects, as in this OED citation from 1888: There’s a good many chores I ‘ant a put down at all. The gutter’s a-stapped again. Is it a feature of Standard English? It is if we recognise, as John Ayto does, that ‘there is both written and spoken Standard English’ (‘The Oxford School A–Z of English’ in Paul Kerswill’s ‘RP, Standard English and the standard/non-standard relationship’ (and, in passing, we might note his there is followed by a compound noun phrase). Ayto cites the use of bust for broken as appropriate in speech but probably not in writing. He also accepts I didn’t use to like eggs as the spoken alternative to I used not to like egg’, which he recommends for written usage. Similarly, Peter Trudgill describes a sentence such as The old man was bloody knackered after his long trip, while colloquial and informal, as being ‘clearly and unambiguously Standard English’. He contrasts it with Father were very tired after his lengthy journey, which is nonstandard but formal.
I think we can take a similar approach to ‘there (i)’s’ + plural noun phrase. There’s probably good reasons for that (an authentic example) is informal Standard English in a way that There probably be good reasons for that, grammatical in some nonstandard dialects, would not be. If you don’t like informality, you’re entitled not to do so, but the right to be informal should not be denied to others.
Pam Peters goes further. In ‘The Cambridge Guide to English Usage’ she writes that
various uses of ‘there’s’ with plural (or notionally plural) noun phrases show how the structure is working its way into the standard. It seems to be evolving into a fixed phrase, rather like the French ‘C’est . . .’, serving the needs of the ongoing discourse rather than the grammar of the sentence.