Re: Shouldn't have to explain
This a bit misleading. Consultants don't pick FOSS products because they're free to make more money. It is possible to make more money out of the savings but it seldom happens because of healthy competition.
My consultancy rate is the same regardless of whether my client pays for licenses or not. In some cases my consultancy rates can be cheaper because I don't have to deal with 1st party support contracts and sitting on hold etc.
I usually suggest FOSS products because:
a) They're the right tool for the job. Why bastardise IIS into becoming a reverse proxy when NGINX has specific features for this particular use case?
b) FOSS saves time. Nobody has to phone around to get quotes for licenses, set up an account with a distributor etc etc etc. This saves money without anyone having to take a hit (other than the vendors). You can save weeks worth of time which translates into potentially tens of thousands of pounds worth of lost time.
c) Better and wider choice of support. If you use. FOSS product and it's a very popular FOSS product there's an excellent chance that there are tons of organisations out there that support it, you don't have vendor lock in. Pissed off with support at one org? No problem, go and hire another. Pissed off with the support on a proprietary product? Well you're stuck, because nobody other than the vendor has the same insight into the product and therefore cannot provide the same or better levels of support.
d) You can customise it, usually relatively easily. Want to brand the portal for your FOSS platform for extra polish? No problem, it's probably quite straight forward. Want to do it on a proprietary platform? That'll be X for the Enterprise Plus option please.
e) It's way easier to audit. Want to use a disk encryption tool that is audited? No problem, plenty of FOSS projects are independently audited and there is transparency. Want to know if Bitlocker is secure and free of backdoors, weaknesses etc...sorry no transparency, auditing etc. you have to hope for the best. Want the source code to have it audited yourself? Sorry, that's proprietary, you can't.
f) There is no phone home brick wall. There's a huge number of proprietary applications that won't work if they can't phone home. Especially if you purchased them through the Windows Store etc.
g) Choice and flexibility. A lot of FOSS products have drop in replacements that you can roll out in a heartbeat. Apache not quite right? No problem, try lighthttpd, nginx etc instead. Debian too heavy? No worries, try Alpine, Arch etc instead.
There are so many benefits outside of "it's cheaper" that I don't accept that "FOSS is used to make more money" as a reasonable argument.
Why on earth would anyone choose vendor lock in, annual renewals, add-on packages, subscriptions etc over FOSS? The only valid reason is if s feature isn't available any other way or your hands are tied for hardware reasons...i.e. you need to use a very specific set of hardware that will only work with very specific products. These use cases are typically "niche" though, they are not the norm.