More correct:
Of the big tech companies, only Amazon structures its RSU so it's heavily backloaded.
Since initial grants are larger (roughly 2x) than refresher grants, the equal vesting of the initial grant (old behavior) could cause a significant drop in compensation for new hires after 4 years at the company (the dreaded equity cliff). This would only happen for relatively "flat" performers, as if you're on an upwards trajectory the larger size of later grants would eventually catch up to your initial equity grant.
Let's say the sign on equity was 200 shares, and refreshers were 100. With equal vesting it would look like:
Year 1: 50 shares
Year 2: 50 + 1 x 25 = 75 shares total
Year 3: 50 + 2 x 25 = 100 shares total
Year 4: 50 + 3 x 25 = 125 shares total
Years 5+: 4 x 25 = 100 shares total (20% drop!)
The problem has actually been worse, because grants are actually in dollars and the stock has been growing consistently year over year. Which means earlier grants are worth more in dollars in later years than new grants, despite having the same dollar value at the time of issue. Let's say 20% yoy, which is not far off from average over the last 10 years. We'll work in dollars and say the initial grant was worth $200K at sign-on time and later grants worth $100K.
Year 1: $50K = $50K
Year 2: $50K * 1.2 + $25K = $85K
Year 3: $50K * 1.2^2 + $25K * 1.2 + $25K = $127K
Year 4: $50K * 1.2^3 + $25K * 1.2^2 + $25K * 1.2 + $25K = $177.4K
Years 5+: $25K * 1.2^3 + $25K * 1.2^2 + $25K * 1.2 + $25K = $134.2K (23% drop!)
With the frontloading this becomes:
Year 1: 66 shares
Year 2: 66 + 1 x 25 = 91 shares
Year 3: 44 + 2 x 25 = 94 shares
Year 4: 12 + 3 x 25 = 87 shares (7% drop)
Years 5+: 4 x 25 = 100 shares
With stock appreciation this becomes:
Year 1: $66K
Year 2: $66K * 1.2 + $25K = $104K
Year 3: $44K * 1.2^2 + $25K * 1.2 + $25K = $118.4K
Year 4: $24k * 1.2^3 + $25K * 1.2^2 + $25K * 1.2 + $25K = $132.5K
Years 5+: $25K * 1.2^3 + $25K * 1.2^2 + $25K * 1.2 + $25K = $134.2K
So the dip is entirely smoothed over. Add in natural increases do to career growth and you no longer notice it.
For the record I work at a different big tech company and was given a massive sign-on bonus. I also have received an offer from Amazon in the past. I know how to read levels.fyi so I'm not sure what it is that I'm missing exactly.
Amazon: 100k base, 250k stock over 4 years (5-15-40-40), ~175k sign-on over 2 years
Other: 100k base, 400k stock over 4 years (25-25-25-25), ~25k sign-on immediately
Essentially the lack of stock over the first 2 years is offset by the sign-on
The point is that while Amazon may offer you a higher signon in lieue of equity, at other FAANGs the choice can be both.
FWIW I've seen recently (in the past year or so) non-AMZN FAANG sign-ons well north of $200K (split over 2 years), along with a top-of-line stock package that vests linearly.
Overall, AMZN's backloaded vesting schedule may be "evened out" via the use of generous signing bonuses, but ultimately is still uncompetitive with other FAANGs. More generally AMZN's TC - no matter which way you cut it - tends to trend lower than competing-tier peer companies.