They should be. Just replace every word "lobbying" with "bribing" and you will see it yourself.

Many of us like it when the EFF, ACLU, Nature Conservancy, or <insert your favorite cause> group lobbies.

We do not consider that bribery, yet when a group we dislike does the same thing, we’re supposed to see all lobbying as bribery or just that of opposing groups?

<Edited to add brevity.>

There are certainly forms of lobbying that are not bribery. Conflating the two is a false equivalency. Lobbying, in general, is the process of informing politicians about certain topics important to an interest group or set of individuals / constituents. When lobbyists bribe (which is illegal) or more realistically: when lobbyists conditionally contribute campaign donations, those actions are the moral hazard.

The problem with lobbying in general is that it's a one-sided information stream: politicians are generally uninformed about a topic and only get the information from the wealthy side (ie. the one able to pay a lobbyist). No need to bribe in general, just overwhelm the poor politicians with "facts" and they have no choice but to walk in line.

To play the devil's advocate: without lobbying, politicians instead get that information from whoever happens to have the resources control the narrative through astroturfing and media manipulation.

Lobbying is at least transparent in its intentions.

Great, now it's "informing". So please tell me, why does this "informing" with some real action afterwards happens only when "informing" side is wealthy? The answer is - because politicians expect tangible, personal real life benefits after such action. Maybe not now, maybe years later, but every one of them does. That's basically bribery with extra steps, it always was and always will be so.

...because you changed the words, you will see it for yourself?

Just because it's hard to put into words doesn't make it not cheating. The fact is society evolves and it takes time to discover the negatives of a lot of business models. People who exploits such models already have the benefit of our non-retroactive judicial system.

Writing a letter to your representative arguing for lower taxes: cool. Making large contributions to their campaign fund, paying them tens of thousands of dollars for a 30 minute speech at your conference etc: not cool.