You seem to be confusing the Eurozone with the EU. The latter has its problems but is a basically sound institution, whereas the former was and remains a terrible idea without a fiscal union.
So you are suggesting that Poland should give up its financial stability (like being pretty much only EU country which did not suffer recession during 2008 financial crisis) and join Eurozone just to help you avoid small inconvenience with reimbursing business trip in foreign currency?
The Eurozone is suffering. All economic areas have up and downs. Being in a shared monerary union, you sacrifize some advantages for others: we compromise - I know, strange word.
We are building a stable, long term monetary union. We are learning, we are improving and we will have a strong currency going forward.
Next time another economy area is in distress, as it will unavoidably happen, remember about our crisis, and how we together saw it through.
Nowadays it is fashionable to attack the Euro. When the crisis is mastered, all know-it-alls will praise it. We do not need to care for the ones or the others. We do our thing.
And yes, the most practical consequence for induvidual citizens is that I do not care about currencies, at all. Except when I travel to Poland.
That sounds rather over-optimistic. A currency union is inherently unstable if not matched to a fiscal union. If you're not going to move to a fiscal union (and after Greece, I'm pretty sure there is not the political will to do so), then the Euro union cannot be stable.
Can it survive even if it's unstable? Perhaps. Will it be worth it? That's not for me to say. But you cannot "master the crisis" with the Euro zone without a fiscal union.
Thanks to the magic of currency markets, I don't have to care about currencies either when I travel in Europe, even though I am American. Whenever I buy something, I use my credit card, and the charges are automatically converted to USD based on whatever the USD/EUR/GBP/etc rates are on that day.
The Eurozone can be a great idea, if some sort of fiscal union comes into being; otherwise the Euro will always be undervalued in the North and overvalued in the South, causing imbalances in investment and consumption.
So are the carrots you buy ecpensive? In april? Two years ago? Basically, you go to the supermarke, get your carrots and say: whatever, lets just get over with it.
Sure, you can get use to a new currency - it took us the best part of a decade to stop thinking in our old national currencies in the eurozone, and some people, and for some things, old currencies are still used mentally and in conversation.
The good thing in the Eurozone is: I dont need to. A currency must, above all, get out of my way.
Not a difficult problem: I just look up the latest local-to-USD conversion rates and do the conversion. If you have a largely cash economy, sure, multiple currencies are a bit of a hassle, but with electronic payments and on-the-fly currency conversion, you can do your accounting in whatever currency you want. It does not get in your way. Having a permanently over- or undervalued currency does.
And I give up on balancing my books with my detailed expenses (cash, credit cards, ...) there. I just have a big “Poland expenses, 1250 €“ entry.