For most registered accounts, you can designate a beneficiary in the event of your demise. Is it possible to do the same for a regular bank or high-interest savings account without creating a will? An example might be one is saving up for a large short-term purchase and has tens of thousands of dollars sitting in a savings account as cash.
In Canada, I had a shared account with my wife at TD Bank. We had the account set up with "right of survivorship". When my wife died suddenly, the bank account became solely mine and did not make up part of her estate. The major advantage here was that I was able to immediately access the bank account to pay for funeral expenses; three and a half months later, I am still waiting on life insurance.
You certainly can grant "power of attorney" over specific bank accounts, but I believe this would allow the person access while you are still alive.
I cannot speak with first-hand authority on designating a beneficiary if the account is not shared, but this is something that my late wife's bank, CIBC, checked when I investigated. Be warned that it can take weeks or months (or, indeed, years, though I hope not) to sort out the paperwork after a person dies.