Considering Vouchers for my tour but it works out more expensive than using cash. And I have read that B&B get a reduced rate for the vouchers. So wouldn't be better for us to pay cash and for the B&B owner, so the B&B owner would prefare not using them. Why do they use them? It seem stange to me if it true.
I'm glad to hear you are enjoying my website. Vouchers are always a big topic for everyone planning a trip to Ireland. You are correct on all counts. Generally vouchers cost more than just paying cash at B&Bs as you go. B&Bs receive only a portion of their full rates from the voucher companies for the room and don't make as much as if a cash paying customer spent the night. You will be better off avoiding vouchers and paying as you go. Also, since not all B&Bs accept vouchers you will have many more options for lodgings open to you and not be restricted.
So why vouchers? Sometimes (usually off-season) vouchers are a good deal as part of an all-inclusive fly/drive/voucher package. Most of the time they are not a deal but on occasion they are. In the off-season when B&Bs are empty they would rather have people staying with vouchers and get a reduced rate simply to avoid having an empty room. At least they make something rather than nothing. Travel agents love vouchers because they get a commission and make money on them.
I hope that clears it up. Take a look at my "Lodgings" page for great places to stay in Ireland.