Your first argument is, again, very American-centric - yes the rate that wealth inequality is growing in the USA is less pronounced than in other places, but it was always pretty bad in the USA. The argument that "trends are similar in almost every developed country" is also a little disingenuous - it's true for the G8. In many European countries, they're actually taxing the wealthy sensibly and putting that money into public services to make everyone's lives better, the wealth gap is much smaller and the quality of life and happiness of regular people is better.

Again "a century ago" or longer doesn't matter because it's pre-industrial revolution. The total amount of "wealth to go around" was much smaller, and we were living under very different systems.

If a king or an emperor owns 50% of the wealth of a nation, and everyone else is equal, then yes, your graph will show "the top 1% have 50% of the wealth" but also your system is specifically designed to give all the money to one person. Arguing "well 100 or 200 years ago this was worse" is moot, because we're comparing different systems... Unless your point is that our current system is also designed to deprive all wealth and comfort to the masses to enrich a select few, and we should be "thankful" that it's less good at it.

We have to compare within the same system, and look for the best we can do. Unless you're specifically arguing that the wealth distribution in the 1970s is unsustainable, then that's an example of when we were capable of doing better, and it's okay to find that as something to aspire and build towards.

Lobbying your representatives for better worker protections is a joke, especially in America. Many representatives in the USA don't even hold surgeries, you can't talk to them directly. You can write them a letter, which they ignore. Rich corporations pay our representatives massive donations to their campaigns (or in other countries, they pay them via more circuitous routes), and they get the policy that benefits them.

Here's an example - Back at the start of the Trump administration, a bill was written by the house to make it legal for ISPs to sell your private information and browsing history to corporations for their own profits. A number of polling institutions went around and took some credible large-scale polls of public opinion about this. 98% of respondents opposed the bill. The legislation passed congress and is now law. Who's "lobbying" of congress matters? individuals, or Comcast?

There are a very small number of US representatives who refuse to take money from large corporations - and those, in general, seem to hold the interests of the people to heart. Before "lobbying your representatives" can work, there needs to be widespread grassroots movements to elect more of these people. Until that happens, there aren't representatives, there are rulers.

It's not inflammatory to argue for better systems. It's not a lie that while we've had a massive industrial revolution that increased the productivity of workers, those benefits have not been seen by the workers. We still work just as long, and just as hard, for an ever diminishing amount of the pie. You can say "oh but you have a fancy car" but... just look at the percentage of people who own their own home by generation. The current trends are extremely concerning and need to change.