Getting Money In and Out of Investment Platforms

Why do I have to wait to get money in and out of investment platforms?
Sharesies is the quickest, I send funds from my bank account, they show in my Sharesies Wallet an hour later.
Similarly, I can process a withdrawal at mid day, it can be in my bank account by 6:00 PM.

Hatch is different as they use USD, so I deposit funds Monday night, they show in my Hatch account Tuesday evening, missing out on a US trading day.
Withdrawals take three times as long, as I have to wait two US working days until funds are cleared, and another four working days until funds appear in my bank account.
I processed a withdrawal Wednesday just been, however due to the US Thanksgiving holiday, I only got the email saying it was being processed today, and will get another one in four days time, which means I’m broke for the weekend and won’t get the funds until Wednesday at the earliest.

I should be able to link my Sharesies and Hatch accounts with Debut, and the API’s talking directly.
So if I want to deposit $10 into Sharesies or Hatch, I move money into the appropriate buckets, and it shows in those accounts ready to invest. Since Hatch uses USD, I get the best exchange rate from Debut instead of Hatch.
Similarly, if I want to withdraw funds, I move them from either bucket, and they show up in Debut ready to use.