For jobs that Amazon hires people there isn’t a technology to automate right now.
Such technology is being developed (better AI and better robotics), but increasing the budget wouldn’t necessarily speed things up.
They are not willing to pay to upgrade all the old FCs, new international FCs, etc. i.e. “it’s too expensive”.
This is also clear in how Amazon waited till the pandemic to add self checkout counters to many Whole Foods. They spent “$4 BB on safety measures for employees” and called self checkout a safety measure to reduce employee to employee density and employee to customer contact. Again it was previously “too expensive to do in mass” even if only for the terrible press it would have brought out side the pandemic.
Not saying “they will never get to it.” They will. Or that it’s not worth it. But the other commenter is also right that unions and hire wages could drive a larger investment in automation earlier than it would have otherwise.