If I call my local representative on the phone, or email them, that's lobbying. Am I not allowed to contact those I've elected to represent me?

Now, if you mean I shouldn't be allowed to take my representative on a Caribbean vacation, then we're agreed, because bribery is (or should be) illegal. And yes, I'm including many forms of campaign donation as "bribery".

What do you mean "a problem that doesn't need to exist"? What's the specific problem you are thinking of?

Trade and especially the shared European market required industry input which you might call lobbying. Regulations had to be homogenized to create a level playing field. To attack what matters European law makers needed lobby input. This happens all the time on a smaller scale with trade agreements. Think of the famous chlorine-washed chicken in the US situation. If a country prohibits this their chicken industry might want a for-export exemption when a trade deal with the US is made.

You also have lobbying that could be seen as genuinely good. Insurance companies lobbied for a lot of car safety standards and fire safety standards. (That said I'm libertarian enough that I don't actually see enforcement of standards that protect the occupant by law as positive but most people do)

Lobbying is the foundation of democracy. Technically it is everyone's civic obligation to do it.

The trouble with democracy, of course, is that most people don't have (or don't think they have, at least) the time or resources to participate.