If you are young, you can easily live off $50k/year, if you don't have children, don't own a car, take the bus to work, and your employer provides health insurance. Food is not that expensive, and you can rent an apartment for 20,000-25,000/year.
If your take-home is 110k, you'd have saved up for a downpayment in 4 years.
starting total compensation: 150K. If your partner works a similar job, your combined annual income is 300K.
No income tax in Washington State, so Federal + FICA taxes would be ~70K (look up any online calculator).
Rent ~1800 per month or 22K per year (based on Zillow's data for 1bd/1ba in Redmond, WA). Living expenses of 2K per month or 24K per year.
You are looking at 300K - (70 + 22 + 24)K, or >180K potential annual savings. Let's double the living expenses or throw in student loan repayments on top, but saving 100-125K per year is easily doable for such a couple. And in a couple of years, you have 200-250K for your downpayment.
Where on earth is someone on $150k, renting, going to get £200k in cash?