Cost is a factor for sample size in any field: but physicists don't publish if they can't accumulate a sufficient sample. As a result physics experiments where sufficient sample sizes can't be obtained are, simply, never performed - and as a result physics as a field grows in the direction of high-certianty.

Physicsts absolutely could be performing experiments with poorer statistics; it'd be cheaper, more advanced things would be done sooner, and we'd be having a replication crisis.

If the social sciences were willing to go a century without discovering anything exciting, they could achieve whatever level of certianty they wanted on their current budget. (At the expense of new discoveries.)