It's entirely possible that for your purposes, Go doesn't yield much of a benefit. I see that "healthy margin" fall out of a bunch of different aspects rather than one big aspect:
1. Working with basic static type support helps me to not worry about silly errors which helps me move faster. Beyond that, it helps team members understand each other's code correctly--when working with dynamically typed languages, type documentation would often be incomplete or become outdated/incorrect and I would spend a lot of time trying to understand the correct type. Moreover, static typing enables a lot of IDE tools that save a ton of time (e.g., goto definition). This is probably more of an advantage for more complex applications rather than simpler CRUD apps.
2. Performance. I've worked on a lot of Python projects where we've spent a lot of time optimizing, and all of the options for optimizing Python have hidden pitfalls (e.g., typically "just rewrite the slow parts to use multiprocessing/C/etc" end up slowing your program down because the costs of marshaling data exceed the gains never mind the costs of maintaining that code). Idiomatic, unoptimized Go is already 10-100X faster than Python and you can pretty easily squeeze more performance out of it via parallelism or moving allocations out of tight loops). If application performance isn't important to you, then this probably won't be particularly compelling.
3. Deployment artifacts. By default, Go compiles to single, reasonably small, static binaries so you can pretty easily build and distribute command line tools to your entire team, you can build tiny Docker images (tiny images mean shorter iteration loop in a cloud environment), etc.
4. Simpler Docker development workflow. With dynamic languages, there's not a great way to iterate. Normally, you'd want to mount your development directory in a volume, but Docker Desktop (or whatever it's called these days) will eat all available CPU marshaling file system events across the VM guest/host boundary, so you end up having to do increasingly convoluted things.
5. Employing and onboarding. Anyone from any language can be productive in Go in a few hours. No need to restrict your hiring pool to "Go developers". Moreover, for other languages, it's not sufficient to merely know the language, you may also have to know the framework, IDE, build tooling, etc that the team uses. The ramp up time can be significant, and this can be a meaningful problem in an industry where people change teams or even companies after a few months or years.
This list is pretty narrowly fixated around dynamic languages because I've done more Python development than I have Java/etc and also because your point of reference is PHP. It's hard to compare Go generally to all other languages.
It was fun to read your response compared to mine :) You mentioned some things I missed, and we had pretty different reasons. Just shows a well made tool carries a variety of values for a variety of users.
1. Working with basic static type support helps me to not worry about silly errors which helps me move faster. Beyond that, it helps team members understand each other's code correctly--when working with dynamically typed languages, type documentation would often be incomplete or become outdated/incorrect and I would spend a lot of time trying to understand the correct type. Moreover, static typing enables a lot of IDE tools that save a ton of time (e.g., goto definition). This is probably more of an advantage for more complex applications rather than simpler CRUD apps.
2. Performance. I've worked on a lot of Python projects where we've spent a lot of time optimizing, and all of the options for optimizing Python have hidden pitfalls (e.g., typically "just rewrite the slow parts to use multiprocessing/C/etc" end up slowing your program down because the costs of marshaling data exceed the gains never mind the costs of maintaining that code). Idiomatic, unoptimized Go is already 10-100X faster than Python and you can pretty easily squeeze more performance out of it via parallelism or moving allocations out of tight loops). If application performance isn't important to you, then this probably won't be particularly compelling.
3. Deployment artifacts. By default, Go compiles to single, reasonably small, static binaries so you can pretty easily build and distribute command line tools to your entire team, you can build tiny Docker images (tiny images mean shorter iteration loop in a cloud environment), etc.
4. Simpler Docker development workflow. With dynamic languages, there's not a great way to iterate. Normally, you'd want to mount your development directory in a volume, but Docker Desktop (or whatever it's called these days) will eat all available CPU marshaling file system events across the VM guest/host boundary, so you end up having to do increasingly convoluted things.
5. Employing and onboarding. Anyone from any language can be productive in Go in a few hours. No need to restrict your hiring pool to "Go developers". Moreover, for other languages, it's not sufficient to merely know the language, you may also have to know the framework, IDE, build tooling, etc that the team uses. The ramp up time can be significant, and this can be a meaningful problem in an industry where people change teams or even companies after a few months or years.
This list is pretty narrowly fixated around dynamic languages because I've done more Python development than I have Java/etc and also because your point of reference is PHP. It's hard to compare Go generally to all other languages.