IMO largest weakness of Joplin mobile is that there are too many extra clicks before you can edit a note.
Imagine that you are in corridor of shop making notes on shopping list with one hand while pushing trolley with other hand. You open Joplin, then open note, then would want to tap where you want to write and start writing. Standard Notes (and possibly Simple notes) work like this.
After tapping note title, Joplin opens note viewer. Then you would have to tap editor logo in upper right, which is even for right handers hard to reach with thumb but for left hander like me it is almost impossible. Then after that you lift your thumb down and possibly scroll a little bit and then tap and keyboard opens and you can finally start writing a note.
Here are suggestions how to solve it:
Configuration - Appearance - "open editor instead of viewer when opening a note" checkmark setting
This would make editing much easier for those of us for whom viewer is not that important and make UX more similar e.g. to standard notes.
Configuration - Appearance - "tap in viewer to open editor" checkmark setting.
As single tap in viewer seems to be mapped nowhere this approach would be also possible but it is one extra tap compared to 1.
Option two is not technically feasible as far as I know but option one is already available if you go to "Settings → Editor → Default view / edit state". You probably have it set to viewer, but editor or last used would probably be better for you.
The premise for your request is a bit different, but there are some technical limitations which would make tap to edit feel like a disjointed user experience in my opinion, see Preserve view / cursor position when switch between view mode and edit mode - #16 by mrjo118
Also, for users that want to use edit mode most of the time, and switch to view mode on demand, how would you suggest to switch to switch from edit > view mode without a button?
A permanent floating button to switch between modes at the bottom was considered, but to be honest this gets in the way too much in edit mode, especially if you open up search or find and replace, which already takes up alot of the bottom of the screen.
option one is already available if you go to "Settings → Editor → Default view / edit state".
Yes, this is what has been implemented to appease users which find having to manually switch to edit mode every time annoying, and it also doubles up as a way to make it easier for 1 handed users / large phone users to not have to constantly toggle a hard to reach button.
For users that want to switch between edit and view mode constantly, this doesn't really solve anything though. But the long term goal is for inline markdown rendering to fully support markdown features, so that there isn't a need to switch between modes while editing.
On a side note, you gave Standard notes as an example to follow, but Standard notes has a hamburger menu at the top of the screen, unlike what you're requesting in your other post Android/ios: hamburger / 3dot bar to bottom. I think that even modern apps don't put a button for every single commonly used function at the bottom of the screen, as it's just not practical from a UI and appearance perspective. Another example is the gmail app which has the hamburger menu at the top left. As a right handed user I either have to switch hand to open the hamburger menu, or temporarily switch to using 2 hands.