The A05 simply doesn't have the chip. As for why? This is a phone you can get for under £80. It's simply not going to have the same features as other phones.
Being a forum for Samsung users—customers, nobody can really give you a definitive "why."
You could get a phone case where your card sits behind your phone. Then you could tap your phone as if it had nfc, but the card would be the thing being read
