Ha, with all your "restrictions and focus" on a very specific niche you might well be right. But as I got an impression we are generally talking about financial firms that are engaging in trading financial assets I took the general view. I have worked at 5 large international investment banks in the capacity of flow trader, quant trader, and prop trader in both fixed income and equities, and at an undisclosed hedge fund, and have quite a number of close friends who work at several hft firms and hedge funds. Nowhere are interpreted languages used for any production and mission critical code that goes into the apps used to run the back, middle, or front ends. We should not confuse use cases where, for example, reports are generated and some guy in product control or so applies VBA macros or other Python code to customize things for specific traders or risk people. But that is an entirely different beast from stable production code that is audited and takes months/years to move into a stable production environment. I would be curious if you could name a single product on the front-end side that is available for purchase for production environments that is written in Python or VBA. If at all then it is individual apps that specific people use to make their lives easier. But certainly not production code on which clients execute millions of, for example, algo orders or risk management values/stresses trading books on a firm-wide and often global basis.
Most items on your list would only apply to interpreted language usage in very small firms/teams that either can't afford expensive proprietary software or do not have the budget for large IT teams. Such smaller firms might "stitch" things together here and there but I highly doubt this qualifies as production and mission critical code that a seasoned senior management and risk management division would ever sign off on. Heck, in most firms it takes weeks/months to just get a hard disk purchase approved and any hardware/software that is implemented in production environment goes though multiple layers of rigorous vetting, testing, and approvals before it is employed. I would claim that a trader at any mid- to large sized hedge fund would immediately get fired if it was found that he himself "altered" the order submission process by applying some sort of hack via interpreted languages to tailor to his/her preferences.
Your last statement definitely is a reflection of your own limited view of things at your firm or the few people you spoke to. Applications/software in research/development are in almost all cases strictly delineated from production code. R or Python are hardly EVER used in any production trading environment at any reputable firm, whether bank, hedge fund, or hft firm. Please name a few firms that programmed their OMS or order routing/execution in Python, I would love to learn and am happy to stand corrected. I am pretty sure you won't find all that many. Or perhaps a few firms that injected some interpreted language hacks into the pipeline of data sourcing (Blomberg pipe/Reuters RMDS -> backend apps in production). Other than at the consumer end in research/development nowhere in this pipeline are interpreted languages to be found.
Re frontends, yes, most firms spend a fortune on developers and technology to get the front ends right as well. All the technology is wasted and money lost when traders or support staff find a hard time to enter their trades and make adjustments on agreed trades with counter parties, for example. None of those front ends are written in interpreted languages either.
Sle, I do not mean to differ with you constantly on issues but it appears several times now that we differed and when laid out my arguments you restricted the universe to a few niche cases. Your points might all be valid in small offices where there might be budget constraints but at most reputable banks, hedge funds, and hft firms and especially on the buy side where the issue of fiduciary duty is more than anywhere else adhered to, interpreted language hacks are just not acceptable business practice. (and yes, VBA and other script code and interpreted languages are nothing but an unstable hack and should only be utilized when mistakes or errors are acceptable)
I think you have a rosy view of big firm's production applications. I've seen some god awful frontends that are complete garbage. Most likely these big firms would benefit from using more modern programming languages for a large portion of their code base and then optimize the parts that need optimizing.