I wouldn't have said this if the offer level was, say $10k or $20k. But $30k seems pretty good even if you have decided that you require the ability to buy a house (not everybody has that privilege; you should feel lucky, and not take it for granted).

It is an offer. It gives you and your family certain benefits. You may also have certain costs. Those are your business. Just deal with them, or not.

You can take it or leave it. If coming to California is worth it for you and your family, take the offer. If not, don't. Not every opportunity in life is cost-free for you. For some of them, you have to step up and pay some of your own contribution.

That being said, your concerns are all valid. These are all things you need to consider, and it's good you're thinking it through. Maybe you can present them to your prospective employer as inputs to your decision. Just don't give them the feeling that you have a very entitled attitude, although you seem to, because that could backfire either with a withdrawn offer, or feelings of rancor later.

Why do you say that?

It sounds like he doesn't want to be out of pocket for a relocation.

He has an upper middle class job and lifestyle and is moving for an upper middle class role. So he wants an upper middle class relocation package.

The cost of relocation is the cost of relocation. That's any cost incurred by the process of relocating. In that person's case, it includes rent. Your case is different. End of story.

Yes, it's possible to move with an economy class ticket and a backpack. Indeed that's how I moved to the US, but expecting your employees to do this is typically not considered a good way to attract talent.

Simple, it could all be arranged within days.

My employer paid for my flight (at £80 or so, including my bike, on the nice airline), plus the cost to move my furniture.

The paperwork was putting my new address on a form, and ticking the box labelled "EU citizen".